OTTAWA (Reuters) - Canada has expressed its "grave concern" to Kabul that Afghan security forces are regularly freeing senior Taliban captives, a Canadian official said on Wednesday.
Reuters revealed on Tuesday that senior Taliban prisoners were being released either for payment or for political motives, with President Hamid Karzai and his powerful brother among those authorizing and requesting releases.
One of the freed men was Ghulam Haidar, a top insurgent in the southern Taliban heartland of Kandahar, where Canada has a 2,800-strong combat mission.
Canadian soldiers handed Haidar over to Afghan authorities in March this year, yet days later he was out on the streets.
"The government of Canada has raised the issue of release of high value detainees by Afghan authorities on a number of occasions with senior officials of the government of Afghanistan," said a Canadian government spokeswoman.
She said Foreign Minister Lawrence Cannon "has also directed officials to call in the Afghan ambassador to raise this particular issue as a grave concern".
Afghan officials declined to discuss the case of Haidar.
The revelations of prisoner releases suggest that complex loyalties and widespread corruption are hampering the West's fight against the insurgency.
The whole question of Afghanistan is becoming more and more of a political headache for Canada's Conservative government.
Polls show the combat mission -- which is due to end next year -- is increasingly unpopular. So far 153 soldiers have died.
Around 950 troops will stay behind until 2014 to help train Afghan forces.
"This is why we continue in our efforts to establish law and order by building the capacity of the Afghan National Army and police and supporting efforts in the areas of justice and corrections," said the Canadian government spokeswoman.
Ottawa has struggled since 2007 to fend off allegations that Canadian soldiers broke international law by handing over detainees who they suspected might be abused by Afghans.
This week, opposition legislators reacted with outrage to the news that soldiers had been transferring child prisoners to Afghan authorities.
Reporting by David Ljunggren; editing by Rob Wilson