Pakistan's ambassador to the United States has resigned over claims that he sought Washington's help against his country's military.Husain Haqqani is accused of compiling a memo seeking US help to avert a military takeover in Pakistan following the killing of Osama Bin Laden in May.
The ambassador denied the allegations, which were made by a US-based lobbyist.
The row has put already tense relations between Pakistan's civilian and military leaders under severe strain.
Mr Haqqani was summoned to Islamabad last week - he quit after meeting Pakistan's civilian and military leaders on Tuesday.
"I have requested PM Gilani to accept my resignation as Pakistan ambassador to US," he said in a Twitter post shortly after the meeting.
State television said that his resignation had been accepted.
"I have much to contribute to building a new Pakistan free of bigotry and intolerance," Mr Haqqani said in another Twitter post. "Will focus energies on that."
His resignation follows a meeting with President Asif Zardari and the head of the army and intelligence service heads.
A spokesman for the prime minister's office told the Reuters news agency that Mr Haqqani had been asked to resign and there would be an investigation into the memo.
Mr Haqqani, a close ally of President Zardari, has repeatedly denied any role in drafting or delivering the memo.
However, former US Joint Chiefs Chairman Michael Mullen recently confirmed that he had received a secret communication.
But he said that did not pay any attention to it and took no follow-up action.