The two men, who were not named, were in their 50s and belonged to a group of 15 Germans working for a Singaporean company, a spokesman for the ministry in Berlin said. A third German was injured.

Singapore's foreign ministry said one of the dead may have come from the city-state, while official Vietnamese sources identified the other fatality as a native of Vietnam.

The Wednesday morning blast in two containers of fireworks occurred outside Hanoi's My Dinh Stadium where Hanoi's anniversary celebrations are set to take place.

The government said a Hanoi company, the International Commercial Investment and Services Company (Interserco) had imported the fireworks for the celebration.

Local media showed pictures of a thick cloud of smoke after the blast which sent large chunks of metal flying and shattered windows at least 200 metres (yards) away.

Reasons for the blast "remain unknown," said an Interserco employee, asking to remain unidentified.

"We are waiting for a final conclusion by the investigators."

The government has blamed the blast and fire on "carelessness during the process of transport".

Despite Wednesday's tragedy, local media reported that a rehearsal took place that night at the stadium ahead of Sunday's grand finale.

The show, featuring lasers and thousands of performers, depicts Vietnamese history and will cap 10 days of exhibitions, cultural performances and other events for Hanoi's 1,000th birthday.

"The event will finish with a magnificent display of fireworks in several places around Hanoi," the website of Voice of Vietnam radio reported.

Agence France Presse - Octobre 8, 2010