A Pakistani doctor who helped the CIA find Osama bin Laden has spoken out to demand better conditions in prison and complain of being falsely implicated in a treason case, his lawyer said on Sunday.

Shakeel Afridi also called for access to his lawyer in a letter that his attorney Samiullah Afridi, who shares his client's tribal name, said was genuine.

Shakeel Afridi was arrested and charged with betraying his country after US troops killed Al-Qaeda leader bin Laden in the town of Abbottabad in May 2011.

He was initially sentenced to 33 years in jail and given a fine, but a court in the northwestern city of Peshawar overturned his sentence in August and ordered a retrial.

"I have been arrested and implicated in a false case," said Afridi in the letter, a copy of which was obtained by AFP.

"I am perhaps the first Pakistani who has been denied access to his lawyer. What kind of justice is this," said the letter.

In the letter, Afridi argued it was his legal right to see his lawyer, and said: "I am a (government) officer and a respectable Pakistani citizen".

He called for access to better conditions and security in jail.

He also said he did not know on what basis his sentence had been overturned.

Afridi was recruited by the CIA to run a vaccination programme in Abbottabad in the hope of obtaining DNA samples that could help identify bin Laden, although medics never managed to gain access to the family.

The doctor was convicted of treason under Pakistan's tribal justice system in 2012 -- not for working for the CIA, for which the court said it had no jurisdiction, but for alleged ties to militants.

A tribunal is set to hear an appeal from Afridi on December 9 seeking a fresh investigation prior to retrial.

Afridi is also facing a murder charge, after authorities in Peshawar on November 23 charged him with killing the son of a tribal woman.