Residents said the soldiers seized control while the country’s president, Fradique de Menezes was away on an official visit to the Nigerian capital of Abuja.
The country’s Prime Minister Maria das Neves and several other key officials were immediately taken into custody as the heavily armed soldiers patrolled the capital, having taken control of the television station, airport and the central bank.
Coup leaders cited tough socio-economic conditions and political instability as the reasons behind the coup, heralded at dawn by a short spell of gunfire and grenade explosions around the capital.
Sao Tome has been hit by political turmoil lately, fuelled by wrangling over what may be billions of barrels of oil lying off its coast. No oil has yet been found though.
Neighboring Nigeria, which will help Sao Tome develop the potential reserves as a joint venture, condemned the coup and cautioned its leaders against harming Nigerian citizens of property.
State of Emergency
The apparent coup leader, Major Fernando Pereira, declared a state of emergency on national radio and told members of the government to gather at the police headquarters.
Defence Minister Fernando Danqua and Parliament speaker, Dionisio Dias were also taken into custody by the soldiers.
On a visit to Portugal, Sao Tome’s Foreign Minister Mateus Meira Rita demanded power be returned to the elected government.
He linked the coup leaders to the Democratic Christian Front, a party which launched protests earlier in July calling for the government’s overthrow.
In a country of 170,000, Sao Tome’s armed forces number about 900 troops.
Some young army officers had taken over the impoverished country for a week in 1995, protesting against backbreaking poverty.