The Economic Community of West African States (ECOWAS) has condemned Sunday's attempted coup in Guinea, and has demanded swift return to constitutional rule.

The bloc has also ordered the immediate and uncondtional release of President Alpha Conde, and all other persons arrested in the power seizure by unnamed soldiers calling themselves the National Committee for Reconciliation and Development.

"ECOWAS reaffirms its objection to any unconstitutional political change," said a statement issued in Accra by Chairperson of the ECOWAS Authority, President Nana Addo Dankwa Akufo-Addo of Ghana.

"We ask the Guinean defense and security forces to remain in a constitutional posture, and express our solidarity with the Guinean people and their Government," the statement said.

The soldiers, reportedly led by a former French Legionnaire, Lieutenant Colonel Mamady Doumbouya, announced that they had seized power and arrested 83-year old President Conde, and suspended the Constitution of the West African nation.

They appeared on national television, with some draped in the red, gold and green flag of Guniea, to announce that the Government had been dissolved because of unbridled corruption.

Those behind the coup said that all land and air borders had been closed for a week.

However, according to a BBC report, the Defence Ministry said forces loyal to the president had "contained the threat and repelled the group of assailants".

Earlier, the only bridge connecting the mainland to the Kaloum peninsular, which houses most ministries and the presidential palace, was sealed off while many soldiers, some heavily armed, were posted around the palace, a military source told Reuters news agency.

There are unconfirmed reports that three soldiers have been killed.

President Condé was re-elected for a controversial third term in office amid violent protests last year.

The veteran opposition leader was first elected in 2010 in the country's first democratic transfer of power.

Despite overseeing some economic progress, he had since been accused of presiding over numerous human rights abuses and harassment of his critics, the BBC said.