US President Barack Obama to press US Congress for action on Islamic State

US President Barack Obama administration officials will hold briefings this week and next for members of the US Congress as the president makes his case for an offensive against Islamic State militants, congressional aides said on Monday.

Administration officials will hold a briefing for all 435 members of the US House of Representatives on Thursday, a House aide said. Senate aides said a similar session for the 100 members of the Senate is planned as early as Wednesday.

President Barack Obama will deliver a speech to Americans on Wednesday laying out his "game plan" to halt the Islamist group that has seized swathes of Syria and Iraq, as he tries to head off public concerns that the country could be moving toward another full-scale war.

On Tuesday, Obama is meeting with the four leaders of Congress - Senate Majority Leader Harry Reid, Senate Minority Leader Mitch McConnell, Speaker of the House John Boehner and House Minority Leader Nancy Pelosi.

The Senate Armed Services Committee announced on Monday that the Secretary of Defense, Chuck Hagel, and General Martin Dempsey, chairman of the Joint Chiefs of Staff, would testify on Sept. 16 at a hearing on U.S. policy toward Iraq and Syria and the threat posed by the Islamic State.

John Kerry, the US Secretary of State, is due to testify the same day before the House Foreign Affairs Committee.