WASHINGTON: A conservative senator called on Tuesday for the United States to suspend all aid to Pakistan and grant citizenship to a doctor who was jailed for helping hunt down Osama bin Laden.

American lawmakers have already sought to cut or freeze some assistance to Pakistan, the third largest recipient of US aid, after a tribal court last week sentenced CIA recruit Shakil Afridi to 33 years in prison on treason charges.

Senator Rand Paul, a Republican from Kentucky and leader of the Tea Party movement, proposed going further by ending all aid to Pakistan until Afridi's sentence is overturned and also granting the doctor US citizenship.

“Pakistan must understand that they are choosing the wrong side,” said Paul, who pledged to introduce the bill when the Senate returns to session next week.

“They accuse Dr. Afridi of working against Pakistan, but he was simply helping the US capture the head of al Qaeda. Surely Pakistan is not linking their interests with those of an international terrorist organisation,” Paul said in a statement.

The US Constitution under Article 1 gives Congress the right to set a “uniform rule of naturalization,” but it is unusual in modern times for lawmakers to consider citizenship for individuals other than honorary titles.

The United States has provided more than $18 billion to Pakistan since the September 11, 2001 attacks when Islamabad agreed to turn against Afghanistan's Taliban and back the US war effort.

But US officials fear that elements of Pakistan's powerful military and intelligence services still support extremists - concerns reinforced when US forces killed Osama bin Laden in the garrison town of Abbottabad last year.

Leading members of both major US parties supported a 2009 bill that authorized $1.5 billion a year to Pakistan to promote civilian infrastructure and democratic institutions in the nuclear-armed nation.

US President Barack Obama, a Democrat, has also voiced impatience with Pakistan. He refused to hold substantive talks with President Asif Ali Zardari at a recent Nato summit in Chicago as Pakistan has not reopened its border with neighboring Afghanistan, stopping supplies from reaching international troops.