(CNN) -- Military leaders and a group of political parties in Guinea-Bissau have announced the formation of a Transitional National Council after a recent coup plunged the African country into deeper chaos.
The announcement came after a group of 22 mostly opposition political parties met with the military command on Sunday. The composition of the transitional council will be determined following another meeting Monday, TNC spokesman Fernando Vaz said.
The president of the council will be the interim president of the country until parliamentary and presidential elections are held, Vaz said.
The formation of the TNC effectively means that the Constitution will be suspended -- a scenario similar to events in 2003, after a coup against then-President Kumba Iala.
And pending approval by the group on Monday, the council "will dissolve all institutions, including the national parliament," the spokesman said.
Also on Monday, members of the TNC's "diplomatic commission" will meet a delegation from the Economic Community of West African States (ECOWAS) regional bloc -- the first meeting between the junta and an international group.
In a statement released Monday, ECOWAS stressed its "zero tolerance for power obtained by unconstitutional means."
"The delegation will reaffirm ECOWAS' rejection of the coup, which has been widely condemned by the international community ... and impress on the junta to restore constitutional rule immediately," the group said.
Guinea-Bissau is a member state of ECOWAS.
A chorus of world leaders have denounced last week's coup, which occurred just before the second round of a presidential election set for April 29.
Coups and coup attempts are common in Guinea-Bissau since it won its independence from Portugal in 1974.
In the latest coup, soldiers took Acting President Raimundo Pereira and Prime Minister Carlos Gomes Jr. into custody Thursday night, sparking international condemnation.
Both leaders are well and alive, said Daba Naualna, a spokesman for the army's chief of staff. He said a group called the military command was behind the arrests, though it was unclear who its members are.
Leaders of the nation's armed forces have taken control of the nation to ensure stability, according to the spokesman.
"The (army chief of staff) thinks, for the sake of the country, that power cannot fall into the streets and decided to have (the military) play its part in seeking solutions with the political class to resolve this crisis," he said.
On Sunday, the "military command" announced the closure of Guinea-Bissau to all air traffic and maritime circulation from abroad as a matter "of national security and safeguard of the territory of Guinea-Bissau."
The African Union, the United Nations and the United States called for a return to civilian rule and demanded the release of the leaders.
Foreign ministers from the Community of Portuguese-Speaking Countries -- a group which Guinea-Bissau is a member of -- have also condemned the coup.
In a statement, the military command said the revolt was in response to a "secret deal" between the government and Angola.
This "deal" was drawn up to allow Angolan troops in the country to attack Guinea-Bissau's military, a communique from the group said.
This group says the acting president and the prime minister signed the deal and also accuses the African Union -- whose rotating presidency is currently held by Angola -- of supporting intervention by Angolan forces.
Guinea-Bissau's history has been marked by several military coups, and these conflicts have ravaged its infrastructure and economy, leaving it among the poorest in the world.
The nation's first round of voting in a presidential election was held in March, and campaigning for the second round was about to begin. The election was prompted by the death of the incumbent Malam Bacai Sanha in January after a long illness.
Residences of the prime minister and some government ministers were looted, witnesses said. Public media outlets are under the control of the army and are regularly broadcasting statements from the military, witnesses said Friday.
Angola, also a former Portuguese colony, issued a statement last week saying it would unilaterally withdraw its troops. A number of Angolan troops are in the country to help reform the country's armed forces, Angola said.
Sanha had become president in September 2009 after the assassination of his predecessor.
Despite his coming to power in what international observers deemed a fair and peaceful election, his tenure was marked by turmoil among the country's military and political leadership.
To date, no democratically elected president of the country has served a full, five-year term.
CNN's Kim Chakanetsa and David McKenzie and contributed to this report.