There are no significant peace talks under way with the Taliban, the US ambassador to Afghanistan has said, despite years of western and Afghan government efforts to broker a political end to the decade-long war in the country, and some recent signs of progress.

James Cunningham, the US Ambassador in Kabul, described reconciliation as "a process that hasn't even really begun", although he added that one of Washington's goals is ensuring "at least the beginning of a serious process".

He also hinted at concerns over the unconditional release of some Taliban prisoners held in Pakistan, which was done at the request of Kabul, and was seen as a goodwill gesture intended to help ease the way for negotiations.

"To this point they've had a pretty hands-off kind of approach to the people that they have released," Cunningham said when asked if he was working with Islamabad to ensure the released men don't rejoin the insurgency. "We would have preferred to have greater visibility into that. Still, it's positive that they were released, I think, from the Afghan point of view."

Secret discussions involving US, Afghan, Pakistani and Taliban officials have been underway for months, focused around confidence-building measures, including the establishment of a political office for the Taliban outside the immediate region and the release of Taliban prisoners.

Earlier this month the insurgent group said they were prepared to open a political office in Qatar for the purpose of negotiations "with the international community", and since last November Pakistan has also released three batches of Taliban prisoners. The moves were taken as signs of real progress towards getting peace talks under way after years of false starts, missteps and outright disasters.

Among the most serious pitfalls were Nato's 2010 discussions with a grocer from the Pakistani city of Quetta, who posed as a senior Taliban official ready to broker talks. He was flown to Kabul for meetings and pocketed thousands of dollars in cash incentives.

In 2011, a suicide bomber posing as a Taliban peace envoy killed the Afghan government's top peace negotiator, former President Burhanuddin Rabbani, by hiding explosives in his turban, and then last December an attacker with a bomb concealed in his underwear, also posing as a potential broker for peace talks, nearly killed the country's spy chief.

One advantage of having a Taliban office is that it should reduce the risk of impostors presenting themselves as Taliban negotiators. But there are question marks over what real incentives the insurgent group has to talk, as the western troops are already heading home, and the Afghan security forces are short on key capacities, from bomb disposal to intelligence and air power.

Afghanistan's political landscape may also be dramatically different in two years time, with a new Afghan president set to be elected next year – incumbent Hamid Karzai cannot stand for re-election – and most western troops gone by the start of 2015.

Cunningham, speaking at a news conference to discuss Karzai's recent visit to Washington to meet US counterpart Barack Obama, said the US hoped to start substantial talks soon, but did not give any further details.

"What we would like to see, and what I think the Afghans would like to see, is … if not the conclusion of a negotiation, at least the beginning of a serious process on peace and reconciliation as soon as possible," Cunningham said.

"But so far it hasn't proven possible to bring those pieces together to get that going … We think its important if we can to help get the Afghans get this process underway, and then try to help them steer it to the best result possible."

Cunningham also rejected a claim by Karzai that the US had promised Afghanistan drones, saying pilotless surveillance aircraft came up in discussions about equipping Afghan forces during the trip to Washington, but no decision had been made. If drones were provided, they would be unarmed, he added. © Guardian News and Media 2013