Fighters backing internationally recognized President Alassane Ouattara claimed fresh gains Monday in attacks across Ivory Coast, their biggest offensive yet against his rival Laurent Gbagbo.

Commanders of the Republican Forces said they had made gains in both the east and the west of the country during the day's fighting.

The Lebanese Embassy in Abidjan revealed on Monday that it received a threat by an individual claiming to be speaking on behalf of the “invisible commandos” warning foreign expatriates, especially the Lebanese one, against meddling in the Ivory Coast’s political affairs.

The embassy said in a statement that the letter was received by email, adding that the commandos announced that they were behind the kidnapping and murder of Lebanese citizen Ali Khalil Fawwz.

The United States recognizes President Alassane Ouattara as the rightful leader of the West African nation of Ivory Coast, U.S. President Barack Obama said late Friday.

"Last year's election was free and fair," Obama said in a video message to the leaders and people of Ivory Coast. "And President Alassane Ouattara is the democratically-elected leader of the nation."

The Lebanese Ambassador to the Ivory Coast Ali Ajami assured that the Lebanese expatriates in the African country are safe and they are not being targeted in the violence.

He told As Safir in remarks published on Friday: “The situation is difficult and worrying, but it is not as dramatic as the media is making it seem.”

Fears grew for the safety of civilians in Abidjan, Ivory Coast’s tense economic capital, amid reports about three Lebanese victims in the clashes between supporters of two rival presidents.

Charbel Zainoun, a Lebanese national residing in the African country, told Voice of Lebanon radio station on Thursday about the three Lebanese without saying if they were killed or injured.

Lebanese businessman Ali Fawwaz has been found dead in Ivory Coast's capital Abidjan, Lebanon's state-run National News Agency reported.

Fawwaz's body was found in a river in the Ivorian capital, NNA added.

Fifty people have been killed in Ivory Coast violence over the past week, including 26 in an Abidjan district that has witnessed fierce clashes, the U.N. mission said here Thursday.

"Fifty people have been killed in a week," a U.N. mission official told Agence France Presse of bloodshed in violence since mid-December linked to a dispute over the results of the November presidential election.