BISSAU - Guinea-Bissau's presidential election campaign kicked off Saturday amid a standoff between incumbent Jose Mario Vaz and an internationally-backed government that he fired last week.

The November 24 vote is being contested by 12 candidates, including Vaz, 62, and his former prime minister Domingos Simoes Pereira, who heads the African Party of the Independence of Guinea and Cape Verde (PAIGC).

The PAIGC enjoys a parliamentary majority after it won a March 10 legislative election.

On Saturday, the capital Bissau was calm, though tensions began to rise as campaign volunteers put up posters and drove through the streets with loudspeakers blaring music in support of another former prime minister, Carlos Gomes Junior.

A long convoy of PAIGC all-terrain vehicles meanwhile headed out to campaign in rural areas.

On October 29, Vaz tried to end months of confrontation with the government by firing prime minister Aristides Gomes and his cabinet.

Gomes refused to step down however, and won support from the 15-nation Economic Community of West African States (ECOWAS) regional bloc.

The United Nations, ECOWAS, the African Union and the European Union have rejected Vaz's move, and reaffirmed support for a mediation plan overseen by ECOWAS.

Under that plan the previous government was to manage the election.

The EU said in a statement this week that the "illegal attempt" to dismiss the government "threatens to derail the ongoing electoral process in Guinea-Bissau".

Home to fewer than two million people, the country has seen a series of coups and governments following independence from Portugal in 1974, as well as an 11-year civil war.

Opposition supporters have demonstrated in recent months for an election delay, complaining of a risk of voting fraud.

A clash between police and opposition demonstrators last month left one protester dead.

Vaz has governed since 2014 in Guinea Bissau, which is stricken by poverty, corruption and drug trafficking.

His five-year term ended in June, but he has been allowed to stay on temporarily under the ECOWAS mediation plan.

After firing Gomes and his cabinet, Vaz named former premier Faustino Imbali as the new prime minister. -AFP