Pakistan has a new ambassador to the United States following a controversy about a memo appealing for U.S. help in reining in Pakistan's powerful military.

Officials said Prime Minister Yousuf Raza Gilani appointed former information minister Sherry Rehman to the post on Wednesday, a day after former ambassador Hussain Haqqani resigned.

Haqqani has denied drafting a memo calling for U.S. help in preventing a military coup in Pakistan following the American raid that killed former al-Qaida leader Osama bin Laden. The letter was sent in May to Admiral Mike Mullen, the top U.S. military officer at the time.

The prime minister's spokesman said Tuesday that Haqqani was asked to step down to allow a proper investigation.

Haqqani had been the ambassador to the United States since 2008, and was well-regarded in Washington. He is a close ally of Pakistani President Asif Ali Zardari.

Pakistani-American businessman Mansoor Ijaz described the memo in an opinion piece published last month in the Financial Times newspaper.

In return for U.S. help in preventing a military coup in Pakistan, the memo said a new national security team would conduct a full inquiry into allegations that Pakistan harbored bin Laden. The new team would also hand over top al-Qaida members and ensure that Pakistan's military spy agency cuts ties to the Taliban, the Haqqani network and other groups.

Ambassador Haqqani said Tuesday that he was resigning to bring closure to the “meaningless controversy threatening our fledging democracy.” He added on Twitter that he has “much to contribute to building a new Pakistan free of bigotry and intolerance.”