Pakistan on Monday released another four Afghan Taliban prisoners, including former justice minister Mullah Nooruddin Turabi, as part of a process designed to kickstart peace efforts, a government official said.

"Four Taliban prisoners have been released," the Pakistani official told AFP on condition of anonymity because he was not authorised to speak to the media.

"They include former Taliban justice minister Nooruddin Turabi and ex-governor of Helmand province, Abdul Bari," the official added.

Two sources close to the Afghan Taliban in northwestern Pakistan confirmed that four prisoners had been released but said they did not include Pakistan's most high-profile Taliban detainee, former deputy leader Mullah Abdul Ghani Baradar.

Baradar was captured in 2010 and Pakistani officials have said in the past that no decision has been taken for his release.

Turabi is said to be suffering from poor health. According to the UN website, he was appointed a Taliban military commander in Afghanistan in mid-2009 and was a deputy to Taliban supreme leader Mullah Omar.

Pakistan last month released at least nine Afghan Taliban, officials said.

At follow-up talks between Afghanistan and Pakistan, Islamabad agreed to release more Taliban prisoners to facilitate efforts to end the 11-year conflict between the Taliban and the Afghan government.

Afghan officials have said senior Taliban leaders held in Pakistan could help bring militants to the negotiating table, if released from jail, to end the war as US-led NATO troops prepare to withdraw in 2014.

Support from Pakistan, which backed the 1996-2001 Taliban regime in Kabul, is seen as crucial to peace in Afghanistan after NATO's departure.

The Taliban, who have been fighting an insurgency since the 2001 US-led invasion, refuse to negotiate directly with Kabul, calling the government of President Hamid Karzai a US puppet.

Preliminary contacts between the US and the Taliban in Doha were broken off in March when the militants failed to secure the release of five of their comrades held at the Guantanamo Bay prison on the US base in Cuba.