British troop numbers in Iraq will only be further reduced "if conditions allow", Defence Secretary Des Browne has said.
Ministers still planned to cut the 4,000-strong force during the next six-monthly rotation, he told MPs.
But Mr Browne added: "While the situation on the ground continues to evolve rapidly, and while military commanders continue to assess the changing environment in Basra, it remains prudent that we take time to fully consider further reductions."
British forces are focusing on training and mentoring an Iraqi army division in Basra which is still "months away from becoming fully operational", he said in a statement to the House of Commons.
"Force levels will be kept under review and we will look to make further reductions over the course of the Telic 12 deployment if conditions allow and on the advice of commanders on the ground," Mr Browne added.
Plans to reduce UK troops in Basra to 2,500 this spring were put on hold earlier this month because of concern over unrest in Iraq's second city.
Since then, Iraqi Security Forces (ISF) have been involved in clashes with Moqtada al-Sadr's Mahdi Army militia in Basra over the past few weeks, and have called in assistance from British forces at an air base outside the city.
Mr Browne said the Iraqi forces had established control over "large parts" of Basra and all key routes in and out, and were removing "significant numbers" of illegal weapons.
"The focus of UK forces is on completing the task of training and mentoring 14th (Iraqi Army) Division in Basra so that it develops into an effective force, able to ensure security without the need for our assistance," he said.
"14 Division is still months away from becoming fully operational. We will continue to ensure that our support is tailored as effectively as possible to meeting its needs."
