ISLAMABAD, Pakistan (CNN) -- A senior Pakistani official says his country will release one of the founding members of the Afghan Taliban.

Mullah Abdul Ghani Baradar, who's being held in a secret location, is a controversial member of the Afghan Taliban who used to be the organization's second-in-command, after Mullah Mohammed Omar himself.

Sartaj Aziz, an adviser to the Pakistani prime minister on national security and foreign affairs, said that Baradar could be released as soon as this month. Speaking to CNN, Aizaz Ahmad Chaudhry, a spokesman for the Foreign Office, said: "We have decided in principle to release Mullah Baradar, and he will be released at an appropriate time."

Baradar was captured in 2010 in Karachi, Pakistan's largest city, which is known to be a haven for many militants from across the country and its bordering regions.

This is the second peaceful overture by the newly elected Pakistani government to neighboring Afghanistan. On Saturday, it released seven Taliban figures to facilitate the peace process.

That release came just two weeks after Afghan President Hamid Karzai visited the capital of Islamabad and stressed Pakistan's assistance in a path to peace. Karzai has long pushed for Baradar's release; his government was suspected to be in secret talks with the wanted militant when he was captured.

The Afghan Taliban said that it welcomed the Pakistani government's plan to release Baradar and that it was assessing the wider situation.

"Pakistan's move to release seven top commanders at the weekend and plans to release Mullah Baradar is a positive development. We'll respond as things shape up over the coming days and weeks," spokesman Zabiullah Muajhid told CNN.

In a news conference held before Pakistan's announcement, Karzai spokesman Aimal Faizi said that Baradar's release would be "a positive step by the Pakistani side and would definitely be effective for the Afghan peace process."

A spokeswoman for the U.S. Embassy in Islamabad, Meghan Gregonis, said Pakistan and Afghanistan should have proper coordination to "ensure releases are effected in a responsible manner."

Baradar had been under U.N. sanctions since February 2001, with his assets frozen and travel banned. The United Nations had forbidden selling weapons to him.

CNN's Zahir Shah Shirazi in Peshawar contributed to this report.