KABUL  - A ceremony to mark the complete transfer of a controversial jail from the US to Afghan control was cancelled on Saturday.

The event at Bagram prison had been announced by Afghan President Hamid Karzai who said it would mark the successful culmination of years of work to decide the fate of suspected militants held by the US forces. But the transfer was abruptly cancelled on the day a suicide bomber killed nine people outside the defence ministry in central Kabul during a visit to the Afghan capital by new US Defense Secretary Chuck Hagel.

“We intend to proceed with the transfer once we have reached full agreement,” a spokesman for the NATO-led international coalition said in a statement. Muhammad Zahir Azimi, spokesman for the Afghan Defence Ministry, said the transfer had been postponed for technical reasons. Karzai said this week he would order release of innocent detainees after the transfer though he expected to face criticism.

The US officials have suggested that some released detainees return to the battlefield, and there are fears that the government is freeing suspected militants to help kick-start peace talks with Taliban.

Last September the United States gave Afghan authorities custody of more than 3,000 detainees at Bagram, a sprawling detention centre 50 kilometres north of Kabul.

But the Americans continued to guard 50 foreigners not covered by the agreement as well as hundreds of Afghans arrested since the transfer deal was signed in March 2012.