ISLAMABAD (AFP) - Pakistan will release on Saturday its most senior Afghan Taleban detainee, Abdul Ghani Baradar, a one-time military chief often described as the insurgents' former second-in-command.

"In order to further facilitate the Afghan reconciliation process, the detained Taleban leader, Mullah Abdul Ghani Baradar, would be released tomorrow," Pakistan's Foreign Ministry said in a statement on Friday.

The Afghan government has long demanded that Islamabad free Baradar, whose arrest in January 2010 saw Pakistan accused of sabotaging initiatives to bring peace in war-torn Afghanistan.

Mr Sartaj Aziz, the main adviser to Pakistan Prime Minister Nawaz Sharif on national security and foreign affairs, had told AFP on Monday that Baradar "will be released this week, possibly in a day or two".

His release would bring to 34 the number of Taleban detainees that Pakistan has freed since last year, in what Afghan officials hope will encourage peace talks with Taleban insurgents.

Mr Aziz had said that Baradar would not be handed over to Kabul.

"It is at his (Baradar's) discretion whether he chooses to live here or anywhere of his own choice," Mr Aziz said.

Baradar was arrested in Pakistan's southern port city of Karachi, reportedly in a secret raid by Central Intelligence Agency and Pakistani agents, an operation that was described as a huge blow to the Taleban, who ruled Afghanistan until a United States-led invasion in 2001.

At the time of his arrest, Baradar was reported to have been the Taleban's second-in-command.

There has been little evidence that the release of Taleban detainees has had a positive effect on the stalled peace negotiations, however, and several prisoners are understood to have returned to the battlefield.

Baradar's influence has also been debated after his years away from the fight.