Gabon's government has barred opposition leaders from leaving the country, after a disputed presidential election on August 30 was won by Ali Ben Bongo, the son of longtime leader Omar Bongo.

Interior Minister Jean-Francois Ndongou says the ban was put into place while the government investigates whether opposition members played a role in last week's post-election violence.

One defeated candidate, Paul Mba Abessole, said he was not allowed to board a flight to Ivory Coast on Wednesday.

The government says at least three people were killed and more than 300 arrested in rioting and looting in the oil hub of Port Gentil, before authorities imposed a curfew in the city.

A coalition of 17 former presidential candidates is claiming at least 10 people were killed in the violence and that the  election was rigged.  The group is calling for an international investigation into the deaths and a vote recount.

Opposition candidates included former Interior Minister Andrew Mba Obame, the runner-up in the election, and opposition leader Pierre Mamboundou, who finished third.  Both took just over 25 percent of the vote, while Mr. Bongo won 42 percent.

Ali Ben Bongo's father, Omar Bongo ruled Gabon for more than 40 years, until his death in June.

Critics accused him of using the nation's oil wealth to finance a lavish lifestyle for himself and for family members and political allies while the vast majority of Gabon's people lived in poverty.

The younger Bongo had been a Cabinet minister in his father's government since 1989.

Some information for this report was provided by AFP and AP.