More than 10 militants late Sunday attacked one of Pakistan's main military bases, used by the navy and air force in Karachi, the country's biggest city, a local government official told AFP.

Several blasts and gunshots were heard inside the sprawling military base in the centre of Karachi, a city of 16 million, police and an AFP reporter said.

"It's a terorrist attack. More than 10 terrorists are inside. They have attacked a navy air station located in a Pakistan Air Force base," said provincial home ministry official Sharfuddin Memon.

"One of the four aircraft inside the premises has been damaged," he added.

An AFP reporter saw flames and smoke rising from the base as gunshots carried on being heard.