They were paraded on Serbian television, to the anger of Nato officials, who said this broke the Geneva convention on prisoners of war.

Initially, Yugoslav officials said the three men would be put on trial, either on charges of espionage or of invading Yugoslav territory.

Their capture brought the Kosovo conflict home to the American public for the first time.

US President Bill Clinton said the capture of its personnel would not affect the Nato bombardment against Serbia, but he stressed "America looks after its own".

At first, Nato said the three men were captured illegally by Serb forces while on the territory of the Former Yugoslav Republic of Macedonia.

This line was dropped as officials privately acknowledged that the men might have strayed across the border by mistake while on patrol.

One previous diplomatic mission to release the prisoners was made by the speaker of the Cypriot parliament, Spyros Kyprianou, but came to nothing.

The three Americans are:

Steven Gonzales, a special technician, 21, who comes from Huntsville, Texas. He has been in the army since 1996.

Steven Gonzales left college to enlist

He left his college, Texas A and M - where he won a scholarship - after only one year's study, to fulfil what his friends say was a life-long ambition to join an elite US military corps.

Apparently his family did not want him to enlist, believing he should finish his studies first.

His interests include science and soccer, and friends describe him as a likeable and intelligent athlete with a good sense of humour.

His friends recognised him immediately from his appearance Yugoslav TV on Thursday, because of his protruding ears.

"He used to wiggle his ears for us and make us laugh," said schoolfriend Kelly Williams. "That's how I knew it was him. It was like, you could not mistake those ears."

Both Mr Gonzales' parents work for the Texas correctional system, and prisons all over the state were asked to tie yellow ribbons to their entrances, until the soldiers are released.

Staff Sergeant Christopher Stone, 25, whose wife and five-year-old son live in San Antonio, has been in the army since 1991.

Christopher Stone: Wife and child in US

He is described as a tough and likeable athlete who has the "gift of gab."

During their appearance on Yugoslav TV, Sergeant Stone, the tallest soldier standing in the middle, appeared to have more facial bruising than his colleagues.

At high school he was a member of the cross-country running team, and a club to warn of the dangers of students drinking and driving.

Staff Sergeant Andrew Ramirez, 24, from east Los Angeles, has served in the army since 1992.

Home of tight-knit Ramirez family in east LA

At school he was interested in wrestling and he enlisted in the army immediately after graduation. His hobbies include car maintenance and dogs.

Relatives say Sergeant Ramirez joined the army because he wanted to emulate his older brother, an army veteran who now works as a detective in the Los Angeles police force.

"Those two brothers are very close. It hit home because we're a very united family," Ramirez's great uncle Frank Jasso told reporters.

UN force in limbo

Unpredep dug in on the border for six years

They were members of Unpredep, a 1,000-strong UN Preventative Deployment Force, which had patrolled the borders of Macedonia and Yugoslavia since the Bosnian war in 1993.

Its mandate should have expired last August, but it was extended for six months because of the increasing violence in Kosovo.

The force ceased its activities at the beginning of last month, when China vetoed another extension at the UN.

This was after Macedonia established diplomatic ties with Taiwan, whose independence China does not recognise.