BOGOTA, Colombia (Reuters) -- Colombian soldiers killed at least 15 Marxist rebels in four separate clashes across the country on Tuesday, the army said.

The fighting came as President Alvaro Uribe, popular for cracking down on the guerrillas, prepares to start his second term next month.

The army said the dead rebels were from the 17,000-strong Revolutionary Armed Forces of Colombia, or FARC, which funds its four-decade-old war against the state through drug smuggling, kidnapping and extortion.

No soldiers died in the battles, which took place in four provinces from the southern jungles of Caqueta to the central mountains of Cundinamarca. Thousands of rebels, soldiers and civilians are killed in the conflict every year.

Uribe, who has cut crime as part of his U.S.-backed military push against the leftist guerrillas, is scheduled to begin his second term on Aug. 7, having won reelection in a 62 percent May landslide.