A high-profile American blogger based in Pakistan has accused a senior opposition leader of raping her at his official residence in 2011.
Cynthia Ritchie alleged she was drugged and assaulted by the then interior minister, Rehman Malik, and separately manhandled by two other senior figures in the Pakistan Peoples Party (PPP).
In a Facebook broadcast on Friday night, Ms Ritchie said she had evidence to support her claims and was prepared to give further details to investigative journalists.
A spokesman for Mr Malik said the accusations were baseless and an attempt to damage his reputation.
The allegations sent shock waves through the Pakistani media, with the country's oldest English language paper describing them as a "bombshell".
Ms Ritchie is a prominent commentator in Pakistan's highly polarised and aggressive online political arena. Her claims follow weeks of intense sniping with PPP supporters after the party launched legal action against her for defaming its late leader and former prime minister Benazir Bhutto, who was assassinated in 2007.
Ms Ritchie said she had faced intimidation and harassment from PPP supporters but refused to be silenced.
In an 11-minute speech, she said she had been “raped by the former interior minister Rehman Malik” in 2011 when the PPP was in power. She had also been “physically manhandled by former health minister Makhdoom Shahabuddin and former prime minister Yousuf Raza Gilani while he was staying at the president’s house”, she said.
Giving more detail later on Twitter, she said the incident happened at Malik's official residence around the time US special forces raided Osama bin Laden's hideout in the Pakistani city of Abbotabad and killed the Al Qaeda leader.
Ms Ritchie said she believed she would be discussing her visa, but was given flowers and a spiked drink.
“I kept quiet – who in the PPP government would help me against the PPP interior minister?” she said.
Ms Ritchie said she reported the assault to the United States embassy, "but due to 'fluid' situation and 'complex' relations between US and Pakistan, response was less than adequate". The American embassy declined to comment.
She went on: "I've been engaged to a wonderful man who I met in Pakistan. He encouraged me to speak out, so we can move on as a couple."
Mr Gilani said he had met Ms Ritchie several times at social functions, but rejected her accusation and said his sons would bring defamation action against her.
“A person of my stature cannot think of it,” he said in comments to Pakistani TV. “I may have gone to Presidency to meet the president or with a delegation, and how could such nonsense thing happen there? Can a prime minister ever commit such an act at the [presidential palace]?"
Ms Ritchie's forthright views, often praising Pakistan or attacking opposition parties, as well as her novelty as a white American woman in the rough-and-tumble of the country's online political battlefield, have seen her acquire a large social media following.
She has been in and out of Pakistan since 2009 and worked as a media consultant, film maker and writer.
Her critics allege she is a paid propagandist for the government, or for the country's feared military spy agency, used to attack opposition groups.
Her feud with the PPP intensified after she alleged in a May 28 tweet that Bhutto ordered her bodyguards to rape women who had affairs with her husband.
The party complained to the cyber crime wing of the Federal Investigation Agency, demanding action against Ms Ritchie for "hateful comments and slander". A separate complaint to the police was made for slander.
Ms Ritchie said she had received online sexual harassment and threats of rape from PPP supporters.
She has claimed to have other incriminating information and last week said the opposition Pakistan Muslim League (PML-N) party would not be spared.
“I have a lot of dirt on a lot of people in this country,” she said in her Facebook broadcast.
"You haven't seen nothing yet", she said, addressing those who had insulted her for "having dared to stand up to you".