On Wednesday, the Russian-made MI-8 helicopter hit a military communications mast on the island of Me, around 10 kilometres (six miles) off the coast of Thanh Hoa province, some 200 kilometres south of Hanoi.

"The accident is essentially due to bad weather," an official from the miltary zone number 4 told AFP.

The state-controlled English daily Vietnam News Friday said for its part: "Experts have assumed that the accident occured due to dense fog the crew of the helicopter may have experienced when flying."

All those aboard the helicopter -- 12 officers, a military journalist with the rank of captain and the three pilots -- died in the crash. Their bodies have been recovered.

One of the generals was the commander of Vietnam's military zone number four in the central province of Nghe An. The team was inspecting "combat readiness in the region".

"More or less all the staff of the fourth zone died in the crash" a foreign military source told AFP.

"It appears that the crew spent most of the morning waiting for the weather to get better," the source said.

"Their program was very full. They left when they felt there was a sudden and brief improvement of the weather."

A Vietnamese source said Thursday the insurance company in charge of the military fleet of this zone had refused to cover the helicopter that was allegedly in poor condition.

The Vietnamese army has constantly reduced its budget and forces since the end of the Vietnam War in 1975.

In 2001, seven American servicemen and nine Vietnamese nationals were killed in the accident of an helicopter MI-17 in the central province of Quang Binh. The US soldiers were in a mission to prepare the recovery of Americans Missing in action from the Vietnam war.

In May 1998, Vietnam's chief of staff and deputy defense minister, general Dao Trong Lich, died when a Laos airforce jet slammed into a mountain in the Laos province of Xienkhouang. Fourteen Vietnamese on board, including several other top officials died.

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