The explosion occurred at the Hai Phong power station in the north-east of the country. The plant is currently under construction by a Chinese contractor to the Vietnamese authorities.

"This is the second deadly explosion within a month in this plant," the plant's general director Tran Huu Nam said.

Nam said the explosion occurred on Tuesday when six workers, including one Chinese expert were moving tanks containing chemicals from an old store to a new one. Two Vietnamese workers died on the spot. The other four were in hospital being treated for their injuries.

The explosion blew up the store, damaging the surrounding area and dismembered the two workers who died, according to state-run newspaper Thanh Nien.

The nature of the chemicals involved was not yet clear, Nam said. The Vietnamese authorities had taken samples for testing, but had not yet received a response from the contractor to a request for more information.

The Chinese builders had been violating Vietnam's safety rules, Nam said.

An earlier chemical explosion on July 17 at the same plant killed two Chinese workers and seriously injured two other workers. The case is under investigation by Vietnamese police.

Chinese companies hold 90 percent of engineering, procurement and construction contracts in the Vietnamese industrial sector, including the energy and extractive industries, local media said Tuesday.

Violations of safety regulations are common, reports said.

Deutsche Presse Agentur - August 5, 2010