At least six people have been killed in a firefight after gunmen attacked an army barracks in Guinea-Bissau, military sources said.

They claim the army repelled Sunday's pre-dawn attack just outside the capital Bissau, killing six "rebels".

The fighting lasted for two hours early on Sunday before the rebel troops were defeated by security forces, a military officer who spoke on condition of anonymity said.

There is no indication if any senior officers were involved in the uprising.

Heightened tensions

The raid is likely to further heighten tensions in the West African nation, where the military seized power in a coup in April.

The UN Security Council has recently demanded that Guinea-Bissau's rulers restore constitutional rule [AFP]

Guinea-Bissau was just weeks away from holding a presidential runoff election when soldiers attacked the front-runner's home and arrested him along with the country's interim president on April 12.

No leader in nearly 40 years of independence has finished his time in office in Guinea-Bissau, a former Portuguese colony on Africa's western coast that has long been plagued by coups.

Following the April coup, military leaders agreed with 26 fringe parties to establish a National Transitional Council to rule the country for two years.

But ECOWAS, the Economic Community of West African States, rejected that agreement and instead demanded a 12-month transition that would include the coup leaders in key positions and culminate in a presidential election.

ECOWAS leaders also authorised the deployment of a 600-strong standby force.

United Nations Secretary General Ban Ki-moon told the General Assembly in May that he was concerned about reports of human rights violations by the military junta.

"Let me speak clearly: those responsible for the coup and subsequent violations of human rights will be held accountable by the international community," he said.

Source: Agencies