The United Kingdom plans to send up to 300 troops to join the UN peacekeeping force in Indonesia.

Defence Secretary Lord Robertson on Tuesday admitted the scale of British involvement in military operations in other countries, including Kosovo, limited its contribution.

His remarks were seized upon by the Conservative defence spokesman Iain Duncan Smith, who claimed they amounted to an embarrassing confession.

Iain Duncan Smith: Urging the government to stop trying to police the world

"After a summer of silence, George Robertson has finally admitted that our armed forces are facing a major overstretch crisis, yet he is happy to oversee the commitment of even more British troops to UN duties," he said.

He backed the position of Shadow Foreign Secretary John Maples, who has argued the UK should not send any troops to Indonesia.

Mr Duncan Smith poured scorn on the Labour government's attempts to be the "world's policeman".

He said: "Their efforts to grandstand on the world stage are being done at the expense of our servicemen's welfare, with the result that we are now losing 1,100 experienced men from the army each month."

Lord Robertson says the UK's contribution to the East Timor force is "not insignificant"

He added that Lord Robertson was being "bullied" by the foreign secretary and claimed defence policy was being made "on the hoof".

But the defence secretary argued the UK contribution to the East Timor force was not "insignificant".

He added: "We have got to remember all the time that this is on the far side of the world, that it is a regional responsibility for the countries in the area.