Pakistan's ambassador to the United States has offered to resign amid reports that the Pakistani government sought American help in defusing a possible military takeover.

Ambassador Hussain Haqqani said he would step down in the interest of the nation. He has been summoned to Islamabad to discuss the situation.

Haqqani has denied he was involved in drafting or passing a memo supposedly sent in May from Pakistani President Asif Ali Zardari to U.S. Admiral Mike Mullen, who was then the top U.S. military officer.

A Pakistani-American businessman described the memo in an opinion piece published last month in the Financial Times newspaper, saying Mr. Zardari was seeking U.S. help to prevent a possible coup by the Pakistani military following the U.S. raid that killed al-Qaida leader Osama bin Laden.

Haqqani has been the ambassador to Washington since 2008, and Pakistan has not responded to his resignation offer.

The May 2 raid in the Pakistani city of Abbottabad underscored tensions between Pakistan's military and its civilian government.

Pakistan was not informed about the U.S. special forces operation in advance and condemned the raid as a violation of its sovereignty.