Downing Street says the Royal Marines commander in Afghanistan - Brigadier Roger Lane - is not being replaced ahead of schedule because of criticism over his handling of the operation.

A spokesman said it had been announced as long ago as February that his post would be shared between two men.

Defence Secretary Geoff Hoon has already defended the commander's record in Afghanistan, dismissing claims about his style of leadership.

But the Conservatives have accused the government of hanging a commander in the field "out to dry".

I think that anybody who tries to stick the knife into him... deserves to be criticised themselves

Bruce George Defence committee chairman

Conservative opposition defence spokesman Bernard Jenkin said it was "yet another presentational cock-up".

He suggested that the government had got itself into trouble by overplaying some events in Afghanistan.

"It's a shame that the government's spin has got so far ahead of the operation in some cases that it has undermined the whole credibility of the operation and ultimately this has a damaging affect on the morale of the troops on the ground," he told BBC Radio 4's Today programme.

'Unfortunate'

Liberal Democrat defence spokesman Paul Keetch said it was "unfortunate" that Brigadier Lane's future should be so publicly questioned.

The commander will be succeeded by Brigadier Jim Dutton, who is currently working as a liaison officer to US Central Command in Florida.

Coalition forces in Afghanistan

11,000 troops from 17 countries including: US: 5,000 Canada: 2,200 Britain: 1,700 France, Australia, Denmark, Germany, Norway are also major contributors

Meanwhile Commons defence select committee chairman Bruce George praised the commander's career and said he should not be put in a position where he left his job under a cloud.

"If that was the case I would be appalled," he told Today.

"I think that anybody who tries to stick the knife into him I think deserves to be criticised themselves."

Brigadier Lane has been in his position for just over a year.

An MoD spokesman said the commander was leaving before the end of his expected two-year tenure to give the Marines "more choice" in future appointments.

He will be allowed to stay on in his job until the current phase of operations in Afghanistan is completed.

Brigadier Dutton will then take over at the end of June.

'Tremendous job'

On Sunday Mr Hoon said he had "complete confidence" in the commander, despite claims he faced mounting pressure to sack him.

The minister dismissed as "nonsense" reports that the mission to Afghanistan had become a mess under the brigadier's leadership.

"He is doing a tremendous job in very difficult conditions and he deserves - and gets - our complete support," Mr Hoon said.

The minister also denied claims that the involvement of British soldiers in Afghanistan had been overstated.

The rebuttal was made after Labour MP Doug Henderson said: "There certainly is a suspicion that... there is a need to hype up the success of the operation when probably not a lot has been achieved."

Conservative MP Nicholas Soames accused the government of presenting the operations "as if they were about to embark on D-Day".