Afghan President Ashraf Ghani offered recognition of the Taliban as a legitimate political group on as part of a proposed political process that he said could lead to talks aimed at ending more than 16 years of war.

The offer, made at the start of an international conference aimed at creating a platform for peace talks, adds to a series of signals from both the Western-backed government and the Taliban suggesting a greater willingness to consider dialogue.

Ghani proposed a ceasefire and a release of prisoners as part of a range of options including new elections, involving the militants, and a constitutional review as part of a pact with the Taliban.

"We are making this offer without preconditions in order to lead to a peace agreement," Ghani said in opening remarks to the conference attended by officials from around 25 countries involved in the so-called Kabul Process.

In return for Ghani's offer, the Taliban would have to recognise the Afghan government and respect the rule of law, he said.

The comments represented a significant shift for Ghani, who in the past has regularly called the Taliban "terrorists" and "rebels" although he has also offered to talk with parts of the movement that accepted peace.

The Taliban, fighting to restore Islamic rule after their 2001 ouster by US-led troops, have offered to begin talks with the United States but have so far refused direct talks with Kabul. It was unclear whether they would be prepared to shift their stance, despite growing international pressure.

However Ghani, who recently helped launch the latest stage in a major regional gas pipeline from Turkmenistan, said the momentum for peace was building from neighbouring countries that increasingly saw the necessity of a stable Afghanistan.

Taliban officials have acknowledged that they have faced pressure from friendly countries to accept talks and said their recent offers to talk to the United States reflected concern that they could be seen to be standing in the way of peace.

Ghani said the process would be accompanied by coordinated diplomatic support including a global effort to persuade neighbouring Pakistan, which Kabul has regularly accused of aiding the Taliban, of the advantages of a stable Afghanistan.

Meanwhile, General Joe Votel, who heads the US military's Central Command, on Tuesday said he has started to see "positive indicators" from the Pakistan military, weeks after President Donald Trump ordered the suspension of US military aid to Islamabad.

US officials believe Pakistan's Inter-Services Intelligence agency and other military bodies have long helped fund and arm the Taliban for ideological reasons, but also to counter rising Indian influence in Afghanistan, whose government is backed by the US.

Islamabad denies those allegations.