Afridi has been languishing behind bars for years since helping US agents track Osama bin Laden.

The Pakistani doctor who helped the CIA track and kill Osama bin Laden has launched a hunger strike from his prison cell, his lawyer and family said on Monday.

Shakeel Afridi has been languishing behind bars for years since his fake vaccination programme helped US agents track and kill the Al Qaeda leader in 2011.

"It is to protest the injustices and inhumane attitudes being committed against him and his family," his brother Jamil Afridi told AFP after meeting with Afridi in a prison in central Punjab province.

His attorney Qamar Nadeem also confirmed the hunger strike.

Afridi was jailed for 33 years in May 2012 after he was convicted of having ties to militants, a charge he has always denied.

His sentence was later reduced by 10 years.

Some US lawmakers have branded the case as revenge for his help in the search for the Al Qaeda chief.

The 2011 killing of Bin Laden caused massive embarrassment for Pakistan and particularly its powerful military.

For years Afridi has had no access to his lawyer, while his appeal against his prison sentence has stalled with scheduled court appearances repeatedly delayed.

His family has also complained of being targeted and harassed by authorities over the years.

US President Donald Trump vowed during his election campaign that he would order Pakistan to free Afridi, but since taking office has been largely silent on the issue.

The comments sparked a blistering rebuttal from Pakistan, whose interior minister at the time branded Trump "ignorant" and stated that the "government of Pakistan and not Donald Trump" would decide Afridi's fate.

In recent years Pakistani authorities have cracked down on nonprofits and forced them to leave the country, which analysts say was largely tied to the Afridi case due to the security establishment's fears that NGOs have provided cover for spying.