A lump of rock, a sophisticated spying device, and an embassy left red-faced

The row over allegations of spying by British diplomats in Moscow escalated as Russian officials accused MI6 of reneging on a "deal" over espionage at the end of the Cold War.

The Russian security service, FSB, claimed yesterday that it had decided to "expose" the undercover activities of the diplomats because Britain had flouted an agreement between the two countries not to spy on each other.

But in London security sources maintained that the Russians had themselves been engaged in widespread intelligence gathering in Britain. The sources also claimed that the real motive in using a television programme to make the claims of British spying was to discredit Russian human rights groups receiving active support from the UK.

Russian state TV had shown footage of a fake "rock" left in a Moscow street and allegedly used by British agents to plant a transmitter. Data from the rock was then supposedly downloaded on to a palm-top computer. The method is similar to one used in a David Attenborough wildlife programme to hide a tiny camera inside artificial elephant dung.

Devices like the "rock" have been used in intelligence gathering to send encrypted messages for several years, although it remains unclear why agents should have chosen a Moscow street for their alleged spying operation.

An FSB official told the programme that one of the diplomats identified by Russian authorities had been authorising payments to Russian non-governmental organisations (NGOs) including civil rights activists. The programme claimed to reveal a document which it suggested was an authorisation for the transfer of £23,000 to the Moscow Helsinki Group, a leading human rights organisation which has been a persistent critic of President Vladimir Putin's government.

Asked about Moscow's spying claims, Tony Blair said yesterday: "I only saw on Teletext this morning the business about Russia. I'm afraid you are going to get the old stock-in-trade 'we never comment on security matters'... except when we want to, obviously. I think the less said about that, the better."

Russian security officials, however, were keen to talk about the affair. Sergei Ignatchenko, an FSB spokesman, said MI6 had already been confronted with supposed evidence of its secret activities at a meeting. "They began to deny it and claimed that they weren't working against us at all," he said. "Only after that did we decide to go public. We consider this a breach of our agreements. In essence we were deceived."

One of the alleged spies was the official assistant to the MI6 desk officer in Moscow and had supposedly attempted to recruit Russians as agents. Another one was seen near the "rock" with a rucksack on his back. Soon afterwards a Russian was arrested while looking inside the contraption and later allegedly admitted spying.

The affair comes in the wake of new legislation requiring NGOs to declare sources of income and provide a comprehensive justification of their activities.

Lyudmilla Alexeyeva, the head of the Helsinki Group, accused the Russian government of carrying out a propaganda exercise. "This is an attempt to smear a well-known group with allegations of involvement in espionage activity," she said. "They are preparing public opinion for a government move to close us down which they can now do under the new law."

The Foreign Office in London said: "It is well known that the UK Government has financially supported projects implemented by Russian NGOs in the field of human rights and civil society. All our assistance is given openly and aims to support the development of a healthy society in Russia."

Last year MI5 (the Secret Service) warned the Home Secretary, then David Blunkett, that spying activities by Russians were growing. According to Whitehall sources there were at least 32 Russian diplomats attempting to obtain military and technical secrets. Last May, a Ministry of Defence internal document stated: "The Russian Federal Intelligence Service are assessed to pose a substantial espionage threat to Britain."

Alex Standish, the editor of Jane's Intelligence Review, said: " Vladimir Putin is a former general with the KGB. He has massively stepped up intelligence operations by the foreign intelligence service."

Diplomatic incidents

1917: Communists accused of infiltrating trade unions and Labour Party

1920s: Russians accuse Britain of destabilising Communist government

1945/early 1950s: The Cambridge Five - Kim Philby, Guy Burgess, Donald Maclean, John Cairncross and Anthony Blunt - pass information to Soviets

1960-1971: 27 Soviet embassy officials told to go

1971: Britain expels 105 members of Soviet diplomatic missions' staff for alleged spying

1994: John Scarlett, now head of MI6, expelled from Moscow where he was serving as an MI6 officer

1995: Britain expels 25 alleged Soviet spies; USSR then expels 25 Britons

1996: Moscow expels nine British diplomats for "running a spy ring"; Britain expels four Russians

From poison umbrellas to lipstick pistols

POISON-TIPPED UMBRELLA

Device used to murder the Bulgarian dissident Georgi Markov in London in 1978. He was injected with ricin while he waited at a bus stop, in an operation thought to have been masterminded by the KGB. Markov experienced a sudden stinging pain in the back of his right leg, but continued on his way to work. By evening he had developed a high fever and he died three days later.

THROUGH-THE-WALL CAMERA

The East German Stasi used this camera, developed by the Czechs in the 1980s. The tube of the camera fitted perfectly into a "port" built into a hotel room wall.

WRISTWATCH CAMERA

This cleverly disguised miniature camera, developed in Germany in about 1949, allowed an operative to take photographs while pretending to check the time. It used a circular piece of film with six exposures.

SECRET WRITING DETECTION KIT

To read secret messages, members of the East German secret police used ultraviolet light of different wavelengths in this kit, dating from the 1980s. Operatives were given pens containing special ink that would only fluoresce when viewed under UV lights of a specific wavelength - otherwise, the writing remained invisible.

LIPSTICK PISTOL

The 4.55mm single-shot weapon disguised as a lipstick was used by the KGB and known as the "Kiss of Death". It was first detected at a border crossing in West Berlin and was one of the many ingenious ways of concealing weapons including torches, pens and the rectal pistol encased in rubber and hidden on the assassin's person.

KGB SPY SHOE

Used by the KGB in the 1960s, the heel was fitted with a radio transmitter, microphone and batteries. A maid or valet would plant the rigged shoes and activate the transmitter by pulling out a pin from the heel. The target would become a walking radio station, transmitting all conversations to a nearby monitoring post.

COAT WITH BUTTONHOLE CAMERA

The lens of the KGB's lightweight F21 camera was hidden behind a false button on the front of the user's coat and triggered by a remote shutter release.

COAL CAMOUFLAGE KIT AND EXPLOSIVE COAL

During the Second World War explosive coal was used by the US for sabotage operations. A coal-shaped device packed with explosives was secretly deposited into coal bins at ship or railroad yards behind enemy lines.

TREE STUMP LISTENING DEVICE

A solar-powered listening device disguised as a tree stump was placed by the CIA in the woods near a Soviet military base to capture secret military radio transmissions.