Guinea-Bissau's armed forces chief of staff was killed and several other officers injured when their military headquarters was blown up on Sunday.

General Batista Tagme Na Wai, long-time chief of staff of the tiny West African country's military, had served in a military junta that overthrew ruler Joao Bernardo "Nino" Vieira in the 1990s. After Mr Vieira was returned to power in 2005 elections, General Na Wai had been outspoken in his criticism of the President.

"It is confirmed that he was killed," a diplomat said early on Monday after an explosion rocked the armed forces headquarters late on Sunday.

The former Portuguese colony, with a population of just 1.6 million people, has suffered years of coups and civil strife and has been used in the past few years as a conduit for smuggling Latin American cocaine to Europe.

A witness who heard the loud boom of weapons went to the site and saw that part of the armed forces headquarters had collapsed. Witnesses at the scene said that the blast appeared to have been caused by a rocket-propelled grenade.

Army troops encircled the area and were searching for the assailants, whose identity was unclear. Five wounded people were taken to hospital, the Reuters witness said.

Diplomats and local journalists said that General Na Wai had been in the building for a meeting with senior officers when the explosion occurred.

Military officers quickly ordered two private radio stations in the capital Bissau to cease broadcasting and state television also stopped broadcasting.

"For the security of the journalists, you must close the radio station and stop broadcasting. It's for your own safety," armed forces spokesman Samuel Fernandes told reporters at Radio Bombolom, a private station in Bissau.

"We are going to pursue the attackers and avenge ourselves," he said.

Two diplomats in Bissau said that they heard a loud blast coming from the military headquarters. Later the streets of the coastal capital appeared generally calm, they said.

In early January, the armed forces command said that militiamen hired to protect President Vieira had shot at General Na Wai.

A member of the militia denied that the shooting had been an assassination attempt, but the armed forces command nevertheless ordered the militia be disbanded.

The 400-strong force had been recruited as President Vieira's personal bodyguard by the Interior Ministry after the President was targeted in a machinegun and rocket-propelled grenade attack on his residence in November last year.

The President survived the raid, carried out by dissident soldiers.

Analysts say that political instability has been exacerbated in the past few years as Latin American drugs gangs have taken advantage of Guinea-Bissau's poorly policed coastline and remote airstrips to smuggle cocaine through Africa to Europe.

They say that well-resourced drug cartels with access to weapons, speedboats and planes have been able to secure co-operation from senior officials in the armed forces and Government in one of the world's poorest countries, whose main export is cashew nuts.

Times Recommends

• Mandela’s tribe threatens President Zuma
• The French empire strikes back
• Wife of cheating governor exacts a political revenge