Browne, citing at least in part the escalation in Basra, said the plans to bring British troops home from Iraq could not proceed because the Iraqi army required further monitoring and logistical support, The Times of London said.

The defense secretary noted military strategists made their assessment before fighting broke out between Shiite militias and Iraqi security forces in late March.

"Before the events of the last week, the emerging military advice -- based on our assessment of current conditions then -- was that further reductions might not be possible at the rate envisaged in the October announcement, although it remains our clear direction of travel and our plan," Browne said.

Browne continued, however, to say that a further drawdown in British forces would not be "prudent" considering the current security situation in Iraq, the Times noted.

British forces pulled out of the southern Iraqi city of Basra at the same time U.S. forces embarked on their "surge" strategy meant to create a security environment that would allow the Iraqi government to gain momentum.

Top U.S. officials will brief Congress April 8-9 on the progress in Iraq, and it is expected U.S. military strategists will follow the British in their assessment on force levels.