* Baradar could play key role in Afghan peace process
* Sources say he is in Karachi, reunited with family
* Pakistan PM due to meet Obama in New York this week
By Maria Golovnina and Asim Tanveer
ISLAMABAD, Sept 22 (Reuters) - Mullah Abdul Ghani Baradar, a former Taliban second-in-command released in Pakistan this weekend, is being kept in a safe house in Karachi as regional powers debate what role he could play in the Afghan peace process, sources in Pakistan said on Sunday.
Afghanistan sees Baradar as a respected figure who could use his influence among the Taliban to help coax moderate commanders to the negotiating table and convince warring parties to stop fighting after more than a decade of war.
The whereabouts of Baradar, one of the founders of the Taliban insurgency, has been the subject of speculation since Pakistan announced he would be released some time on Saturday. There has been no official confirmation of his location.
"Mullah Baradar was flown to Karachi from Peshawar early on Sunday. He is being kept in a safe location in Karachi," one Pakistani intelligence source told Reuters.
A government source with knowledge of the situation said separately: "He will not be sent to Afghanistan. He is in a safe house in Karachi. ... Everything will be decided between Pakistan, Afghanistan and the United States."
It was unclear how long Baradar would stay in Karachi, a sprawling and violent port city. Sources had earlier said that he might eventually be sent to Turkey, Saudi Arabia or Dubai to help kick-start peace talks with Taliban representatives.
The government source said Pakistan decided to announce his release to coincide with Prime Minister Nawaz Sharif's visit to New York, where he is expected to meet U.S. President Barack Obama on the sidelines of the United Nations General Assembly.
"The timing of his release was tied to his (Sharif's) departure so that Pakistan is seen as doing all it can (for the Afghan peace process)," said the government source.
Afghanistan has called for Baradar's release for years, and Baradar's captivity in Pakistan has been a source of tension as anxiety grows ahead of a planned withdrawal of most U.S.-led troops from Afghanistan at the end of next year.
Baradar, who is in his forties, was once a close friend of the reclusive, one-eyed Taliban leader, Mullah Mohammad Omar, who gave him his nom de guerre, "Baradar" or "brother", and he still enjoys much respect among Taliban fighters.
An appeal to lay down arms coming from a man of his stature is likely to be treated seriously by commanders in the field, Afghan officials believe.
But some are sceptical, with critics saying his years in detention have eroded his sway over the evolving insurgency. There are also doubts whether real decision-makers such as Mullah Omar, who is himself in hiding, would agree to talk to him.
A source in Afghan President Hamid Karzai's administration said Baradar was kept in "protective custody" by Pakistani intelligence but did not say where exactly.
Known as a calm and level-headed negotiator, Baradar is believed to be willing to play the role of a peace ambassador, having once reached out to Kabul to seek a peace settlement.
A source with the Taliban-linked militancy in Pakistan said Baradar had now been reunited with his family in Karachi, where he was arrested in 2010 in a joint U.S.-Pakistani raid.
"Our brother Baradar has been freed and it is our great victory," the source said.