QUETTA, Pakistan (Reuters) - Gunmen in Pakistan killed six soldiers and a provincial government official in an ambush on their convoy in the insurgency plagued southwest province of Baluchistan, a senior official in the region said on Friday.

The attack took place about 80 kilometers (50 miles) from Gwadar, a port that will play a vital role in a planned $46 billion China-Pakistan economic corridor stretching from the Arabian sea to China's far-western Xinjiang district.

The convoy had been returning from dealing with a land dispute late on Thursday when gunmen fired rockets and hurled grenades at the group, Tufail Baloch, a deputy district commissioner for Gwadar, told Reuters.

"It was a sudden attack. They also used AK-47 rifles," he said. The dead included a senior local government official.

Separatist groups in Baluchistan, a sparsely populated but vast province bordering Iran and Afghanistan, have launched sporadic attacks on security forces during their decades long struggle for an independent homeland.

Pakistan is particularly sensitive to attacks on Chinese workers and interests in Baluchistan, and promised them protection.

Militants have mostly targeted government personnel and security forces during the past decade, but attacks on civilians do occur.

Last year gunmen stormed Jewani airport in Baluchistan, killing engineers and destroying radar systems.

Baluch activists say security forces have carried out hundreds of extrajudicial killings, and thousands of people have disappeared.

(Reporting by Gul Yousafzai; Writing by Tommy Wilkes; Editing by Simon Cameron-Moore)