Afghan security forces in the southern city of Kandahar on Wednesday were fighting Taliban insurgents who raided the city's sprawling airport late on Tuesday, officials said.
Sameem Khpalwak, a spokesman for the local governor, said there had been several casualties among both security forces and civilians but the exact number was unknown because the area had not been secured.
A statement from the Taliban said suicide attackers armed with both light and heavy weapons had entered the base in Kandahar, one of the traditional heartlands of the Islamist insurgency, and had attacked international forces and their Afghan allies.
It said 150 soldiers had been killed but there was no official confirmation and the movement has often made exaggerated casualty claims in the past.
A spokesman for NATO's Resolute Support mission said there had been no reports of casualties among the hundreds of international personnel on the base but he had no other details.
Taliban insurgents attacked a perimeter section of the heavily fortified site, which contains both a civilian airport and a large military base.
The fighters initially took up position in a school building close to the perimeter of the military area of the site in a section that contained accommodation for officials.
The Taliban, fighting to re-establish hard-line Islamist rule after U.S.-led military intervention toppled their regime in 2001, have been struggling to settle a leadership dispute which has seen scores killed in fighting between opposing factions.
But the attack, which coincided with the start of the Heart of Asia regional security conference in Islamabad, underlined the movement's continuing ability to attack key targets after its success in briefly capturing the northern city of Kunduz in September.
The attack follows an earlier incident in which two suicide bombers died assaulting a police station in Kandahar, one of the traditional Taliban strongholds.
