Tens of thousands of people have marched in Pakistan's southern city of Karachi, demanding the release of imprisoned scientist Doctor Aafia Siddiqui.
Dr Siddiqui was sentenced to 86 years in prison by a New York court on 23 September.
She had been convicted of trying to kill US federal agents in Afghanistan.
US officials also say she is an al-Qaeda agent, but her family say this is a cover-up.
According to them, Dr Siddiqui has been a prisoner of the United States since her disappearance from Karachi in 2003.
There have been a number of protests in Pakistan over her case but this rally, organised by the MQM political party, was the largest so far.
The crowd roared as the imprisoned scientist's sister addressed them on a bright Tuesday afternoon in Karachi.
Dr Fowzia Siddiqui called on those gathered to continue their struggle for her sister's release.
She said she was positive that Aafia Siddiqui would soon be back in Pakistan if the public pressure continued.
The rally in Karachi was the latest in a continuing campaign to pressure the US and Pakistani governments.
But it is the first time that a mainstream political party has called for Dr Siddiqui's release.
The MQM is also a part of the ruling coalition.
Its most senior leader in Pakistan, Dr Farooq Sattar, explains why the party has joined the chorus: "America is not a perfect country, American system and their policies are not perfect."
Dr Sattar said US authorities should review many of their policies.
"They are pushing secular, moderate, liberal and progressive people on the other side of the line of divide," he said, "and more and more people are becoming fanatic, becoming extremists and becoming terrorists."
Pakistan's government is now feeling the heat of this fast-growing campaign.
Prime Minister Yusuf Raza Gillani expressed his displeasure after Dr Aafia was sentenced.
He called her a daughter of the nation, and said his government would do its best to get her released.