Don't worry. If you see a flying saucer, it's probably one of ours

An "uninhabited" flying saucer - the Ministry of Defence says that "unmanned" would be politically incorrect - is one of the options being examined to enable the Royal Air Force to attack distant targets well into the next century.

Britain is to spend pounds 35m looking at options for the Future Air Offensive System (FAOS), a new programme launched yesterday, and named to stress that the option eventually decided upon might not be a conventional aircraft. It could be an "uninhabited" aircraft, or an air-launched missile. Two things are certain: it will be stealthy and it will almost certainly have a virtual-reality cockpit - either in the aircraft itself, in a separate aircraft, or on the ground.

The new system is designed to replace the RAF's Tornado bombers in about 2015. "We are looking at something to do the job way into the next century," an MoD source said.

The Defence Procurement Minister, James Arbuthnot, told Parliament yesterday: "Study contracts to the value of pounds 35m are expected to be placed in the new year. Options to be examined include variants of the Eurofighter and other new-design and off-the-shelf combat aircraft, unmanned air vehicles, and stand-off air-to-ground missiles launched from transport aircraft. Collaborative options will be pursued."

Of the pounds 35m, pounds 6m is being spent on a Franco-British programme, pounds 3m with British Aerospace and the MoD's own experts, and pounds 3m with the French alone. Other studies are being placed with industry and the Defence Evaluation and Research Agency.

Britain's Eurofighter partners - Italy, Germany and Spain - will be involved in the studies but so will France, Sweden and the United States. MoD sources said that collaboration with the US on the final aircraft had not been ruled out.

Until now, the US has held the lead in "stealth" technology, making aircraft nearly invisible to visual, radar, heat-seeking and other forms of detection. But the principles of stealth technology are becoming widely understood and European aircraft designers are becoming increasingly expert in putting them into practice. "The secrets of stealth are not so black as they were in the past", an RAF officer said, referring to the top-secret US "black programmes".

The new system is needed to attack targets at greater range than will be possible with the Eurofighter - the RAF's other new aircraft, due in 2002.

During the Gulf War, enormous amounts of effort and money were spent refuelling aircraft in the air, and the RAF yesterday said that the new system needed to operate without so much air-to-air refuelling. The most traditional option is to extend the range and payload of the Eurofighter. But to do that, and to make it more stealthy, might involve so many changes to the airframe that it would be more cost-effective to bring in a completely new plane, either from the US, or built in Europe.

That is the second option. The third is the uninhabited aircraft, which could return home and be re-armed. The fourth is a long-range air-launched missile, probably dropped from a transport plane.

The RAF is well-provided with weapons to drop, including the conventionally armed stand-off missile and the Brimstone anti-tank missile, which was given the go-ahead earlier this year. The new aircraft will also carry precision-guided bombs - either laser-guided or with inbuilt systems which enable the bombs to put themselves in exactly the right place.

The aircraft is also expected to carry "non-lethal weapons" to disrupt computer systems and confuse enemy troops and headquarters without casualties.