NATO has temporarily stopped transferring detainees to a number of Afghan jails after a new report, yet to be published, uncovered accusations of torture and abuse NATO and United Nations officials said Tuesday.

The United Nations Assistance Mission Afghanistan centred its evaluation on at least six detention centres run by the National Directorate of Security, Afghanistan's main intelligence agency, and three jails operated by the Ministry of Justice.

NATO officials have refused to provide more details about the report but confirmed they will investigate the findings, which have be passed on to officials from the Karzai government.

"With appropriate caution, I.S.A.F. has taken the prudent measure to suspend detainee transfer to certain facilities until we can verify the observations in a pending Unama report," NATO said in a statement, referring to the NATO-led International Security Assistance Force.

Also commenting on the report was UN spokesman Dan McNorton who said "We understand that they are taking the findings extremely seriously and are proposing a series of remedial actions,"

"Our findings indicate that the mistreatment of detainees is not an institutional or government policy of the government of Afghanistan."

Prisoner transfers in parts of NATO's southern regional command which include the Taliban hotspot of Kandahar had already been stopped in July, but following the new findings, another 8 facilities are now affected.

The announcement came as the country is expected to be under the control of the national forces by 2014.

The findings do not come as a shock as human rights groups and activists have for long warned that Afghan prisons were over-crowded, with problems such as inmate violence and allegations of violations of basic human rights coupled with abuse and torture by the Afghan forces are rife.

Prisoners are often forced to live in extremely precarious conditions, which have worsened with the rapid growth of the prison population which has gone from 600 prisoners in 2001 to about 19,000 in 2011, according to figures from the UN.

The afghan police and army have been plagued by problems of endemic corruption, desertion, drug abuse and illiteracy for years and the security forces have so far struggled to bring the violent insurgency led by the Taliban to a halt.

In April, hundreds of prisoners escaped from jail in Afghanistan's southern, Kandahar, through a tunnel dug by the insurgent group and while officials called the incident a "disaster," many suspected guards of being aware of the escape plan.

As NATO backed the Karzai government it has invested in programmes aiming at improving the security forces' performance but despite millions of dollars and training by the Alliance personnel, clearly much more progress are needed before Afghanistan can built a solid violence free future.