Lawyers for a Pakistani doctor jailed after he helped U.S. agents track down Osama bin Laden have appealed his conviction.

A tribal court in the northwestern Khyber agency last month sentenced Shakil Afridi to 33 years in prison on charges of colluding with Islamist militants. Court documents say he met with commanders of the banned Pakistani militant group Lashkar-e-Islam and gave them medical treatment and financial help.

Afridi's appeal, filed Friday, denies the charges. It says he had no links with Lashkar-e-Islam and was in fact kidnapped by the group in 2008 and ordered to pay a ransom of more than $10,000.

A VOA correspondent quotes Afridi's brother as saying Friday that the charges against his brother are baseless. Jamil Afridi expressed confidence he will be set free.

Shakil Afridi was also accused of running a fake vaccination campaign to help U.S. authorities obtain DNA samples of bin Laden and members of his family in order to confirm the al-Qaida leader's presence at a compound in the Pakistani city of Abbottabad. U.S. special forces raided the compound last year and killed bin Laden.

Initially, Pakistani officials and media reported Afridi was convicted of treason for conspiring with foreign intelligence agencies. On Wednesday, however, local media reported he had been prosecuted for “involvement in anti-state activities” and that the treason charge fell outside the tribal court's jurisdiction. The reports cited a court document.

On Thursday, Lashkar-e-Islam denied having any ties to Afridi. Representatives of the group called him a traitor and enemy of Islam, saying it would put him to death if it had the opportunity.

Rustum Shah Mohmand, a former Khyber agency trial administrator, tells VOA that Afridi's appeal will be difficult because his case will be heard by a commissioner who is a civil servant.

“Civil servants in this country are under the government. They will do whatever the government asks them to do.”

The United States has criticized Afridi's conviction and called for his release. However, Mohmand says many Pakistani's believe the conviction is justified.

“The public sentiment is very high and most of the Pakistanis would like to see him convicted because in their view, he has brought a bad name to the government institutions. I think the military would be equally keen to have him convicted.”

The jailing of Shakil Afridi comes amid heightened tensions between Pakistan and the U.S. The Pakistani government closed a major NATO supply route into Afghanistan last November after 24 Pakistanis were mistakenly killed in coalition airstrikes near the Pakistani border.

Pakistan has demanded an apology for the cross-border attack and an end to U.S. drone strikes in Pakistan.