There is no question of us withdrawing our troops at this time

Defence Secretary Geoff Hoon

He said they should either send in many more troops and ensure greater safety for them, or - better still - withdraw them all.

Sunday's rescue mission was launched after renegade militia group the West Side Boys had threatened to kill the six British soldiers being held hostage in a remote jungle stronghold. Some 12 other soldiers were injured in the rescue mission.

But Defence Secretary Geoff Hoon insisted British troops would not pull out. Instead, he said more could be sent in.

UN effort 'pathetic'

Mr Duncan Smith told BBC Radio 4's Today programme he backed the initial decision to send troops in to help British nationals flee the fighting and support the Sierra Leone Government while the UN built up its strength there.

Five Royal Irish Regiment troops were released earlier

But he said the troops were reliant on the UN's efficiency, as well as a good relationship with the terrorists.

"The UN have not been capable of securing the area and have been just short of pathetic.

"We either now take the decision to withdraw British troops - which I would favour - and tell the UN to get on with the job they were told to do in the first place, or else we decide, if we put British troops in, they have got to be properly protected.

"As long as British troops are hanging around, it seems to me that the UN think they can rely consistently on British efforts."

UK mission 'nearly over'

Mr Hoon insisted that British troops "still had a job to do", but added that their work there was nearly done.

"There is no question of us withdrawing our troops at this time," he said.

If we put British troops in, they have got to be properly protected

Tory spokesman Iain Duncan Smith

"We have approved three support training missions, two of which have been concluded and one of which is almost under way."

Mr Hoon said: "Once we have been able properly to debrief all the hostages, we will find out precisely why they came to be detained.

"If, as a result of that, we do need to take a different approach to ensuring the safety and security of British troops in Sierra Leone, let me make it quite clear we will do that," he told Today.

Asked if that could mean deploying more British troops, he said: "If that is the judgment we reach, then, certainly, the safety and security of British forces in Sierra Leone is paramount."

Later, Foreign Secretary Robin Cook hit back at the Tories' idea, saying a withdrawal would give comfort to the rebels.

"We are committed to repelling the rebels in Sierra Leone and restoring stability to its people," he said.

'Quality, not quantity'

Britain's involvement in Sierra Leone may last only another six weeks, the estimated time of the final training mission, he said.

Liberal Democrat defence spokesman Menzies Campbell called for Britain to contribute a battalion of troops to the UN force, which is being upgraded from 13,500 to 20,000.

He said: "It is not the number of troops that matters, so much as the quality of the troops. That has been part of the failure of the UN effort - they have simply not had good enough troops to do the job.

"I certainly think we should make a contribution to the UN force. It would make an enormous contribution to morale as well as to numbers and would help the UN fulfil its mandate."