|Many experts question the readiness of Afghan security forces to fill the gap left by a US troop withdrawal [Reuters]
At least six Afghan police have been killed at a checkpoint in an assault likely to raise fresh security questions as the US prepares to pull troops out of Afghanistan.
Another four officers were killed by a roadside bomb as they travelled to the scene in Ghazni province's Qarabagh district, about 120km southwest of Kabul.
Wednesday's checkpoint attack was thought to have been an inside job in which fighters worked with a police officer stationed there.
"Probably one of the police officers at the checkpoint had a previous deal with the insurgents and co-operated with and facilitated the assault," Mohammad Ali Ahmadi, the deputy governor of Ghazni, said.
The Taliban claimed responsibility for the attack.
Earlier this month, three police were killed in a similar attack on their checkpoint in the same district.
The assault came just hours before Barack Obama was to map a course for withdrawing US troops from the nearly 10-year war in Afghanistan, which could lead to the return of 10,000 soldiers to the US this year and another 20,000 by 2012.
But despite concerns from some experts about the readiness of Afghan forces to fill the gap left by the troop withdrawal, General Mohammad Zahir Azimi, the Afghan defence ministry spokesperson, insisted they were well placed to do so.
"We welcome the decision of the people and president of the United States of America regarding withdrawal of a number of troops and we support such a decision," he said in Kabul.
"The national army of Afghanistan has gained the capacity to fill the gap that will come up in some areas after withdrawal of these troops ... we are able to fill the personnel shortage."
Afghan forces are due to take increasing responsibility for security between July, when the transition process starts, and the end of 2014, when all foreign combat troops are planned to have withdrawn.
A senior US official said on condition of anonymity that Obama was "likely" to order the return of about 5,000 troops this summer and 5,000 more by the end of the year.
Summer fighting seasons
Another 20,000 troops, part of a 30,000-strong surge ordered in December 2009, would be withdrawn by the end of next year, meaning elevated force levels would remain through two more Afghan summer fighting seasons.
It would still leave more American troops in Afghanistan than when Obama was elected to office in November 2008.
But sceptics of the war argue that after the deaths of more than 1,600 US service personnel and a cost of nearly $10bn a month, the American commitment is unsustainable at its present size.
According to an Associated Press-GfK poll in May, 80 per cent of the US population say they approve of Obama's decision to begin withdrawal of combat troops in July and end US combat operations in Afghanistan by 2014. Just 15 per cent disapprove.
There are currently around 130,000 international troops in Afghanistan under the NATO-led International Security Assistance Force, including about 90,000 from the US.