Operation Essential Harvest is here for a limited purpose, which is arms collection and confidence building and for a limited period of time

Jack Straw, Foreign Secretary

The dead man's father, Kevin Collins, criticised Nato for using troops in what was a "civil conflict".

A special military ceremony was held in Skopje before the soldier's body was flown back to RAF Lyneham in Wiltshire on Friday evening.

Fellow soldiers acted as pall-bearers and formed an honour guard, which included an American contingent.

Mr Collins said a private funeral, with full military honours, would be held for his son at a later date in Sheffield.

Jack Straw has expressed his regret over the soldier's death, and said he is uncertain whether British troops will leave Macedonia within Nato's 30-day deadline.

He said: "Sapper Ian Collins' death was terrible and would have been terrible at any stage.

"Coming as it did right at the beginning of the operation it was bound to raise, in very dark terms, questions about this operation which otherwise would not have been raised."

Deadline uncertainty

He later added: "The [Macedonian] president repeated his undertaking which he made to the British prime minister on Monday that there would be a very thorough investigation of what had happened."

Sapper Collins: The first Nato victim of the operation

The foreign secretary, visiting Macedonia, said his "best bet" was that troops will withdraw on time but that there was no way of being certain.

After seeing British soldiers and meeting politicians in Skopje, Mr Straw insisted that Nato's Operation Essential Harvest to gather weapons from the ethnic Albanian National Liberation Army was going to plan.

More than a third of Nato's target number of weapons have been collected.

During a news conference in Macedonia, Mr Straw said the Nato operation was "on target" but declined to be drawn on whether British troops would remain in Macedonia if the ceasefire broke down.

"Operation Essential Harvest is here for a limited purpose, which is arms collection and confidence building and for a limited period of time," said Mr Straw.

An honour guard and piper joined the funeral procession

But earlier Mr Straw told the BBC it was possible the mission would be extended.

He said: "Nothing in the Balkans is inevitable.

"It could change, but it took a lot of discussion amongst the partners in Nato to agree this 30 days."

Contingency plans

Later, speaking at a press conference in Skopje after hours of meetings with political leaders, Mr Straw stressed: "Operation Essential Harvest will end within 30 days and that's being made very clear by Nato Secretary General Lord Robertson."

But, again, he added a rider when asked whether there could be further military intervention, saying: "It's unwise ever to say never and I'm not getting into that.

"There are obviously contingency plans for if something goes wrong."

Nato had pledged to gather 3,300 weapons from the rebel National Liberation Army (NLA) within 30 days of its mission.