A NATO base in volatile eastern Afghanistan came under attack early on Saturday from possible Taliban militants, police in the region said.
NATO's International Security Assistance Force (ISAF) was unable to confirm reports that a US-run base in Khost province had come under attack but said it was investigating the reports.
"From what I understand it is still ongoing, we are getting details," a spokeswoman said.
Local police chief Adbul Hakim Is'haqzai told AFP that Taliban militants had first attacked Forward Operating Base (FOB) Salerno before retreating to occupy a secondary school in Khost city, the provincial capital.
The school was near a smaller US-run base, FOB Chapman, he said.
Seven CIA agents were killed in a Taliban attack on FOB Chapman in December, in what was the worst attack on US intelligence officials since 1983, when the US embassy in Beirut was bombed.
The Saturday attack began when insurgents launched rockets and gunfire on Salerno in the early hours of the morning, Is'haqzai said.
He said: "Now the fighting (at Salerno) has slowed down," but there was an ongoing exchange of fire between militants and security forces at the school.
Taliban spokesman Zabihullah Mujahed contacted AFP to say the insurgent group had despatched suicide bombers to the base.
"Twenty-eight Taliban suicide bombers have launched an attack on a coalition base in Khost," he said from an undisclosed location.
"They have entered the base," he said.
The Talban are known to exaggerate their claims.
Khost borders Pakistan, source of fighters, funds and fertiliser to make the ubiquitous IEDs the Taliban deploy along with suicide bombers and targeted assassinations in the war, which is nearing its tenth year.