Kabul: A suicide bomber killed at least six medical students and wounded 23 others at Afghanistan's main military hospital in Kabul on Saturday, the Afghan Defense Ministry said in a statement.

The blast took place in a tent used as a dining room by students at the city centre hospital, one of the biggest and best-equipped in Afghanistan.

The hospital is not used by NATO forces, though it is thought that foreign medics are frequently stationed there to train their Afghan counterparts.

Defense ministry spokesman General Mohammad Zahir Azimi said,"There was a suicide attack at a tent used as a dining facility by medical students inside the hospital.”

He added,"The blast killed six people and wounded 23 others and all of them are medical students."

Responsibility for the blast was claimed by the Taliban, whose spokesman Zabihullah Mujahid said two attackers had entered the heavily-secured hospital.

Mohammad Zaher, head of Kabul police's criminal investigation department, said that searches were still going on at the hospital for another possible attacker.

However, Azimi denied reports that there was a second suicide attacker on the loose in the hospital.

Eyewitness Mohammad Hakim, who has a cart selling fruit nearby, described what had happened.

"It was a big explosion, I fell to the ground," he said.

"The police arrived late at the scene, half an hour after the explosion took place," he added.

The roads to the hospital were blocked and Afghan security forces including the spy agency's quick reaction forces cordoned off the facility, while police and soldierswere also on the scene.

Afghanistan's military are frequently targeted by the Taliban and other militants. There has been a recent spike in suicide bombings, a key Taliban tactic.

Two rockets were fired overnight into Kabul city landing in an empty plot, causing no damage or casualties, interior ministry spokesman Zemarai Bashary said.