The Taliban are "clearly" responsible for violence in Afghanistan, with civilians and Afghan security forces taking the brunt of the bloodshed, the commander of US forces in the Middle East said Thursday.

General Kenneth McKenzie, head of the US Army Central Command (Centcom), made the remark on a regional tour, as President Joe Biden reviews a military withdrawal from the country planned for the beginning of May. 

The Taliban denied being behind the violence which has escalated as US-brokered peace negotiations with the Afghan government stalled, saying those responsible are other jihadist groups.

But General McKenzie has blamed them directly. "Certainly ISIS (the Islamic State group) has launched some attacks. It pales against what the Taliban is doing. It's a combination of their countrywide attacks against the Afghan forces, their targeted assassinations in some of the urban areas. 

"This is clearly the Taliban. There is no way it's anyone else. That's very clear," McKenzie said.

He also said that violence in the war-weary country is "too high now."

"Violence is not directed at us or our coalition NATO friends, it is directed against the Afghan military and security forces and against the people as well. And that is principally coming from the Taliban," he stressed to reporters traveling with him.

The Taliban on Tuesday urged the US to honour a landmark withdrawal deal struck under former US president Donald Trump, which called for US troops to exit Afghanistan in the coming months in exchange for security guarantees.

The deal initially paved the way for the peace negotiations between the militants and Kabul. 

But now Biden's administration is reviewing the accord, while the Pentagon has accused the Taliban of not fulfilling promises that include reducing attacks and cutting ties to insurgent groups such as Al-Qaeda.

A study mandated by the US Congress has called for a delay in the pullout, warning it would effectively hand the Taliban a victory.

With the withdrawal deadline nearing, the Taliban have launched a string of offensives threatening at least two strategic provincial capitals in southern Afghanistan in recent months.

The US and the Afghan government have also blamed the insurgents for a wave of deadly assassinations targeting journalists, politicians, judges and activists.