Pakistan's envoy to the United States says he is flying home to answer allegations he wrote an explosive memo that asked for Washington's help in reining in the Pakistani military.

Pakistan's civilian government has been facing a crisis following a claim by Mansoor Ijaz, a U.S. citizen of Pakistani origin, that he delivered a memo to then-U.S. military chief Adm. Mike Mullen a week after the U.S. raid killed al-Qaeda leader Osama bin Laden in a Pakistani garrison town.

The memo allegedly requests U.S. help in installing a "new security team" in Islamabad friendly to Washington.

Ijaz says that the ambassador, Husain Haqqani, was behind the memo.

Haqqani, who denies he was behind the memo, tweeted on Saturday he was heading to the "motherland". Officials confirmed his return.