Iain Duncan Smith has warned that he has "deep misgivings" about Tony Blair's plans to deploy 1500 troops to a peace-keeping initiative in Afghanistan.

The Tory leader said the troops could become the focus of attacks from defeated Taliban forces.

Blair told the Commons yesterday that the UK was ready in principle to lead a mission which could last several months.

In a move which prompted claims that his plans were falling apart, Blair told MPs that the number of troops required would be in the region of 1000-1500 - half the figure initially estimated.