Mullah Zaeef was the best-known public face of the Taleban
A former senior Taleban official from Afghanistan says he is taking legal action against the authorities in Pakistan over his arrest there in 2002.
Mullah Abdul Salam Zaeef, who was the Taleban's ambassador in Islamabad, says he had diplomatic immunity at the time of his arrest.
It came after the Taleban were overthrown in Afghanistan by United States forces in 2001.
Mullah Zaeef was handed over to the Americans by the Pakistani authorities.
He spent more than three years in detention in Guantanamo Bay.
Mullah Zaeef attended a meeting last month in Saudi Arabia with Afghan officials and other former members of the Taleban.
He became the best-known public face of the Taleban during the US-led campaign in Afghanistan, giving regular news conferences broadcast around the world and providing a line of communication with his isolated and reclusive leaders.
Pakistan was the last country to have diplomatic relations with the Taleban, before its fall from power.
It subsequently closed down all of the Taleban's diplomatic missions in the country.