Madeleine McCann investigation: Parents said to be on 'tenterhooks' amid reports Scotland Yard team is 'set to swoop on three suspects'

Reports that police are seeking assistance to interview the three potential suspects following suspicions raised by phone records

British girl Madeleine McCann, who was allegedy abducted 03 May 2007 from the resort apartment where she was on vacation with her family in the Algarve (Getty Images)

British detectives investigating the disappearance of Madeleine McCann have arrived in Portugal to discuss potential leads with local officers and are 'set to swoop on three suspects’, reports have claimed.

Madeleine's parents, Kate and Gerry, are said to be “on tenterhooks”, according to reports in The Daily Mirror, over a possible breakthrough in the six-year case of their missing daughter after a team from Scotland Yard travelled to the Algarve.

Hopes were raised that a potential development was imminent after British police sent an International Letter of Request to authorities in the country asking for help to trace three burglary suspects spotted in the area where Madeleine vanished almost seven years ago.

"It is necessary for British police to request the Portuguese authorities to allow them to operate on their turf," a source told the Mirror. "It means they have the intention of arresting and interviewing X, Y or Z."

The team, headed by Detective Chief Inspector Andy Redwood, who is leading the Met's investigation, reportedly met members of Portugal's Policia Judiciaria and prosecutors to request help and discuss leads identified by teams in the UK.

It is reported that they are seeking assistance to interview the three potential suspects, though Scotland Yard refused to confirm whether a team was in the country or the purpose behind the travel.

The development follows scrutiny of mobile phone records that revealed the suspects repeatedly called each other in the hours after three-year-old Madeleine disappeared from a holiday apartment in Praia da Luz in May 2007.

Kate and Gerry McCann are said to be 'on tenterhooks' about the possible breakthrough (PA)

The Metropolitan Police launched its own investigation in July into the disappearance of the then toddler. A number of new developments, including crucial changes to what was originally thought to be the timeline around events in the Portuguese resort, were detailed in a BBC Crimewatch programme.

Television appeals in the UK, Germany and Holland last year triggered thousands of calls from the public.

British officers have travelled to the Algarve numerous times since then in the search of the missing girl.

The Portuguese police, which once declared the parents as suspects, shelved the inquiry into her disappearance in 2008, but in October said that a review had uncovered enough new information to justify reopening the case.

Police in Portugal are running their investigation in parallel with the British inquiry but there were calls earlier this month for the two teams to merge.

According to the Mail Online, which claims to have published pictures of the police arriving in Portugal, British officers held a three-hour meeting with senior members of Portugal’s detective squad shortly after arriving on Monday.

A source close to Madeleine's parents, Kate and Gerry, told the Mirror: “Clearly the fact that the police are out there is significant. Kate and Gerry will now be on tenterhooks as they wait for any potential developments.

“The Met are being very pro-active and this is good news in the search for Madeleine and her abductor.”

A Metropolitan Police spokesman said the force was “not prepared to give a running commentary” about the investigation.