Washington: There will be no new announcement on troop withdrawal from Afghanistan during the forthcoming Chicago Summit, the White House has said.

"No announcements of further troop withdrawals will come in Chicago, and there are no options currently under consideration," White House Press Secretary Jay Carney told reporters.

The withdrawal of surged troops would be completed by mid-September and after that 68,000 US troops would remain in Afghanistan, he said.

"The President is focused on implementing a strategy that has as its core objective the goal of disrupting and dismantling and ultimately defeating al Qaeda. As part of this process, he surged up US forces considerably," he said.

"We are now drawing down those forces that surged into Afghanistan, and that withdrawal will be complete by the middle of September. The President made clear that we will continue to withdraw US forces at a steady pace.

"However, the specific timetable for that and troop numbers will not be decided until we have finished the current withdrawal," Carney said.

He said 68,000 troops which will remain after the withdrawal of the surge forces is a good number going into the period of the post-surge-withdrawal period.

"But the President's position has not changed, and that position is that we will steadily draw down US troops as we continue to transition security lead to Afghan security forces as they continue to be trained and their numbers increase," he said.

"What will be discussed and agreed upon we hope in Chicago is a decision to transfer combat lead to Afghan forces in 2013 as part of the full transition to Afghan security control by the end of 2014," he said responding to a question on the forthcoming NATO summit in Chicago in May.