WASHINGTON - Senior Taliban officials have been secretly negotiating with Afghan officials on a possible ceasefire, the commander of US and NATO forces in Afghanistan disclosed Wednesday.

“A lot of the diplomatic activity and dialogue is occurring off the stage, and it’s occurring at multiple levels,” General John Nicholson said in a teleconference with reporters at the Pentagon. He would not identify the figures involved in the negotiations, except to say that they included mid- and senior-level Taliban officials.

“I should point out they met in secret. This is how they were able to advance the talks,” he said, adding that the success of the effort depends in part on the “confidentiality of the process.”

Afghan President Ashraf Ghani in late February proposed peace talks with the Taliban, saying they could be recognised as a political party if they accepted a ceasefire and recognized the country’s 2004 constitution.

The Taliban have not officially responded, but deadly attacks have proliferated since then, particularly in Kabul, which has become the most dangerous place in the country for civilians.

But Nicholson, who has sought to drive the Taliban to the negotiating table by bringing to bear increased US military pressure, maintained that violence and progress can coexist. He likened the situation in Afghanistan to that of Colombia where the fighting continued up until the FARC guerrilla group and the government signed a peace accord in 2016.

On Wednesday, militants launched a gun and bomb attack on the Interior Ministry in Kabul, killing a policeman in another demonstration of their ability to strike at the heart of the Afghan capital.

Five people were injured in the attack, which was claimed by the Islamic State (IS) group.

Special forces rushed to the scene after the attackers detonated what police said was a car bomb at the first checkpoint leading to the ministry, then tried to battle their way inside.

“The fighting is over, the attackers have all been killed by security forces between the first and second security perimeter,” said Kabul police chief Daud Amin.

A security source told AFP a clearing operation was continuing. “The attackers used two vehicles to reach near interior ministry compound. There were eight attackers involved, one detonated his explosives, seven others were killed,” interior ministry spokesman Najib Danish told reporters.

Danish said one police officer had been killed and five civilians wounded. Policeman Mujibullah Nabizada was injured in the first blast.

“I dragged myself to the road and a car picked up and brought me to the hospital,” he told AFP from his hospital bed, where he was being treated for broken bones.

Seweeta Saberi, 17, was also wounded in the blast and taken to hospital. “Everyone is sitting in their loved ones’ blood these days,” her brother Sameer told AFP. “We request you [government leaders], for God’s sake, if you can’t manage this country please resign.”

A security source told AFP there had been multiple blasts but could not confirm how many.

“I was in my office when I heard a blast followed by gunfire. We were told to stay inside our offices as the compound was attacked,” said one ministry employee.

IS, which is trying to make inroads in Afghanistan, claimed responsibility for the attack via its Amaq propaganda service.

Police also said they had found a car stuffed with explosives and guns at Kabul’s international airport near the interior ministry on Wednesday.

Earlier on Wednesday, Taliban attackers including a suicide bomber stormed a police station in southern Afghanistan and killed six police officers. The bomber detonated an explosive-laden vehicle at the entrance of the police station in Puli Alam, the capital of Logar province, said provincial police spokesman Shapoor Ahmadzai.

Three other attackers then rushed into the police station compound, triggering a half-hour gunbattle with security forces, he said.

“In half an hour security forces killed all the attackers. Unfortunately, three national police and three traffic police were also killed. Eight civilians have also been wounded,” he told AFP.