Taliban kills 3 United States soldiers in Ghazni roadside bombing

Interior Ministry deputy spokesman Nasrat Rahimi said casualties were "not known".

"A number of gunmen entered the G4S compound right after the vehicle bomb", said Najib Danish, an Interior Ministry spokesman.

"It is unfortunate and events like this bolster our resolve for peace", said Hamdullah Mohib, the Afghan national security adviser, on the sidelines of a UN-sponsored conference in Geneva where Ghani repeated calls for peace with the Taliban.

He added a suicide bomber detonated his explosives and then other insurgents started a gun battle with forces in the area.

Kabul police spokesman Basir Mujahid said the target of the attack was G4S.

US special operations troops often accompany their Afghan counterparts into battle as part of a joint counterterrorism mission, which is separate from the much larger USA and coalition mission to train and equip government forces battling a 17-year Taliban insurgency.

Trump has acknowledged that his original instinct was to withdraw from Afghanistan, but last week he suggested he is willing to stick it out, asserting that the United States is in "very strong negotiations" - an apparent reference to United States envoy Zalmay Khalilzad's efforts to get the Taliban to agree to peace talks.

"We can confirm that there has been an incident at one of our locations in Kabul".

Resolute Support, the NATO-led mission to Afghanistan, announced three USA service members were killed by an improvised explosive device on Tuesday.

He said US Special Forces had been conducting operations with Afghan forces around Ghazni city since Monday.

The terror group didn't yet have a report about the attack on their website, or a claim of responsibility. "It gives you an idea just how much of a load of this fight is being carried by the Afghan army", he said.

Several of the wounded were in critical condition, Afghanistan's health ministry said.

Security officials have warned that violence is likely to escalate alongside peace moves as the Taliban seeks to strengthen its position before any formal negotiations.