Obama To Meet Congressional Leaders On ISIS: Source

WASHINGTON, Sept 5 (Reuters) - U.S. President Barack Obama will meet with the four leaders of the U.S. Congress on Tuesday, a senior congressional source said on Friday, amid rising concern in Washington about the advances of the Islamic State.

The source told Reuters the meeting would take place at 3:15 p.m. EDT (1915 GMT). Lawmakers return to Washington on Monday from their five-week August recess.

The meeting will include Harry Reid, the Democratic leader of the U.S. Senate, and Mitch McConnell, the chamber's top Republican, as well as John Boehner, the speaker of the House of Representatives and Nancy Pelosi, the House's top Democrat.

The topic of the meeting was not disclosed, but it is expected to focus on the threat posed by the Sunni militants.

Lawmakers from both parties have been calling on Obama to detail his plans for going after the group, which has seized swathes of Iraq and Syria and provoked outrage by releasing videos showing the gruesome beheadings of two American journalists.

Some have criticized the president for failing to present a strategy both to both Congress and the American public.

Obama said at a NATO summit on Friday that NATO allies stood ready to join the United States in military action to defeat Islamic State militants in Iraq as he vowed to 'take out' the leaders of a movement he said was a major threat to the West.

The meeting with the Congressional leadership was first reported by the Washington Post.

(Reporting by Patricia Zengerle; Editing by Robert Birsel)