ABIDJAN, Ivory Coast — Forces loyal to Ivory Coast’s internationally recognized president claimed Monday to have seized a major city, an event that could mark the beginning of military operations in the West African country that has teetered for months on the brink of civil war.

The area along the Liberian border has seen limited fighting for the last several weeks, but the latest push could open the way for troops loyal to Alassane Ouattara to march south to the strategic port of San Pedro, or east to the political capital of Yamoussoukro.

Capt. Leon Alla, Ouattara’s defense spokesman, said the city of Duekoue fell Monday morning.

Incumbent leader Laurent Gbagbo refuses to give up power. Gbagbo adviser Toussaint Alain said from Paris that officials close to Gbagbo told him the city remained under army control and that the rebels were pushed back. He said at least 17 rebels died, a figure that could not be immediately confirmed.

Seydou Ouattara, Ouattara’s military spokesman, said forces have also surrounded Guiglo, a nearby city where militias loyal to Gbagbo pillaged the United Nations refugee agency’s base last week.

“It will surely fall today,” he said, adding that two other cities were being targeted. “The general offensive has begun, because we’ve realized that this is the only way to remove (Gbagbo),” said Ouattara, who is not related to the leader.

Alain, the Gbagbo adviser, said Ouattara’s forces were also responsible for looting in the town.

Monday marks four months since the November election. The international community and numerous observers, including the country’s electoral commission, say Ouattara won that poll. But Gbagbo has steadfastly refused to give up power, drawing financial sanctions from the United States and the European Union.

The standoff has led to daily fighting in different parts of the economic capital of Abidjan, where security forces loyal to Gbagbo have used heavy weapons against the population, acts the U.N. said could be crimes against humanity.

The majority of the 462 killings that have been confirmed by the U.N. were carried out by Gbagbo’s security forces against Muslims and northerners perceived as being supporters of Ouattara, Human Rights Watch said in a report released this month.

Pro-Ouattara fighters, however, were responsible for some revenge killings, the report said.

More than 1 million people have fled the fighting, the U.N.’s refugee agency said last week, most of them leaving Abidjan, where many believe a bloody final battle for the presidency will take place.

Numerous diplomatic efforts to negotiate a peaceful transfer of power have led nowhere, after delegations from the African Union and the regional West African bloc ECOWAS both endorsed Ouattara.