The Taliban and the Afghan government restarted secret peace talks in September and have held two rounds of discussions in Qatar, Britain's Guardian newspaper reported on Tuesday, citing anonymous sources.

Citing a Taliban official, the Guardian said a senior American diplomat was present at the meetings in Qatar, where the militant group has a diplomatic office.

The newspaper said the talks were also attended by Mullah Abdul Manan, the brother of Afghan Taliban founder, Mullah Mohammad Omar, who died in 2013.

An official in the National Unity Government in Kabul said that the two rounds of discussions took place in Doha, where the Taliban maintain a political office.

The Taliban and the US government have so far not commented officially on the development.

The outcome of the September meeting was not clear but a Taliban source told the newspaper that it “went positively and was held in a trouble-free atmosphere”.

A second dialogue was held this month despite intensified nationwide fighting between insurgents and US-backed Afghan troops.

Previous Pakistan-brokered peace talks yielded little progress and came to a complete halt when the United States killed former Taliban leader Mullah Akhtar Mansour in a drone strike in Pakistan in May.

Under the new Taliban leader, Haibatullah Akhundzada, fighting has raged across Afghanistan during the summer months, with the Taliban attacking the northern city of Kunduz and threatening Helmand's provincial capital Lashkar Gah.

No Pakistani official took part in the latest talks, according to the Guardian.

Relations between the governments in Kabul and Islamabad have deteriorated over the past year, with Afghanistan and the United States alleging Pakistan harbours the Taliban and was not doing enough to bring the group to the negotiating table.

Pakistan has denied allegations of providing the Taliban a safe haven.

The Taliban have gathered strength over the past two years, carrying out major attacks in Kabul and taking over swaths of territory for the first time since being ousted during the 2001 US-led military intervention.

The United States has continued to provide air power and other military support to Kabul, preventing the Taliban from making more ground.