LIBREVILLE, September 7, 2009 (AFP) - Gabon's opposition demanded Monday a recount in the country's hotly disputed election and charged that the government is trying to cover up a "bloodbath" following the vote.

The government said at least three people died during riots that erupted after ruling party candidate Ali Bongo was declared the winner of the August 30 vote, succeeding his father and longtime ruler Omar Bongo who died in June.

But Bongo's main challengers charged that the government was hiding the real number of deaths and called for the creation of an international investigative panel to determine "who is responsible for this bloodbath".

"The number of deaths caused by the army repression is much higher than the government would like to say," said a declaration signed by 16 candidates that was read by former prime minister Jean Eyeghe Ndong.

Bongo was declared the winner of the election on Thursday with 42 percent of the vote, followed by former interior minister Andre Mba Obame with 26 percent and opposition leader Pierre Mamboundou with 25 percent.

The government said Monday that Ali Bongo had received a letter of congratulations from French President Nicolas Sarkozy -- a key endorsement from a country that had close ties to the elder Bongo during his 41 years in power.

"Following the announcement by the constitutional court of the presidential election results, I am happy to address to you my congratulations and wishes of success in fulfilling the responsibilities that await you," read the Sarkozy letter shown to AFP.

But the coalition of 16 losing candidates, which includes Mba Obame and Mamboundou, repeated their charges that the election was fraudulent.

They said in their declaration that the election was marred by "grave manipulations" and charged that there was a "scandalous stuffing of ballot boxes" as well as an "incomprehensible swelling of voter lists".

"We demand a recount of votes that was interrupted by the president of the CENAP (electoral commission)," they said.

Mamboundou made his first public appearance in four days at a press conference in the capital Libreville on Monday.

His Union of Gabonese People party had expressed fears for his life after saying it had not seen him since police dispersed an opposition protest outside the offices of the electoral committee on September 3.

The announcement of Bongo's victory last Thursday sparked days of violence in Mamboundou's stronghold of Port-Gentil, Gabon's coastal oil hub and second city.

A precarious calm returned to Port-Gentil on Monday after the government threatened to invoke emergency powers to quell the unrest.

Troops patrolled the streets while some shops began to-reopen and store owners picked through the wreckage. But banks and many other shops remained shut.

"I've lost everything," said fruit seller Justine Obame.

"The first night they burned everything in the area. The next night, they came back to take what they had left behind. I have 13 children and I don't know what I'm going to do."

Taxis and some civilian traffic returned to the streets and flights resumed from the peninsular seaport after being suspended last week.

The poorer areas of the city bore the brunt of the violence, with dozens of cars, shops and market stalls burned out by rioters angry at France's perceived influence in bringing another Bongo to power.

The city's French consulate and social club for workers of French oil giant Total were torched last week. Dozens of fearful residents fled Port-Gentil aboard motorized canoes at the weekend.