Clashes between the army and rebels loyal to a renegade former general in eastern DR Congo have killed 18 people, military sources said on Monday, in the latest violence before crucial elections to replace President Joseph Kabila this month.

Fighting killed 14 rebels and four soldiers in Fizi, a region of South Kivu, a mineral-rich province which is prone to ethnic tensions, the sources said.

Fizi, Democratic Republic of Congo

The sources said one soldier and two rebels were killed early Monday in fighting.

Earlier, army spokesman Captain Dieudonne Kaserek, told AFP 12 rebel fighters were killed including a deputy commander known as Alida. He said three of the soldiers drowned in a river during combat.

Violence in the troubled eastern region is just one complication before December 23 elections in DR Congo, which has not seen a peaceful transfer of power since independence from colonial Belgium in 1960.

FILE - Congo's President Joseph Kabila, seen in th Congo's President Joseph Kabila, seen in this July 19, 2018 file photo, has said he will support former Interior Minister Emmanuel Ramazani Shadary in the upcoming presidential election. Congo's President Joseph Kabila, seen in this July 19, 2018 file photo, has said he will support former Interior Minister Emmanuel Ramazani Shadary in the upcoming presidential election.

Under international pressure, Kabila has agreed to step aside, but critics worry he will try to engineer a win for his handpicked successor, former hardline interior minister Emmanuel Ramazani Shadary.

The eastern clashes pit the military against rebels loyal to a former army general, William Amuri Yakutumba, whose militia is one of the armed groups operating in the region against Kabila.

The militia is allied to rebels of the National Liberation Front based in neighboring Burundi, according to several regional sources.

In September of last year the Yakutumba rebels attacked the town of Uvira on Lake Tanganyika opposite the Burundian capital Bujumbura. UN forces pushed them back with Congolese support.

In February the military said they had wiped out the Yakutumba with help from Burundi, where some of them had taken refuge.

Trading accusations

Western powers are closely watching the presidential election in the vast mineral-wealthy nation, where a UN peace-keeping force, now with 16,000 troops on the ground, has been operating for two decades.

Kabila's second and final elected term finished nearly two years ago, but he has remained in office thanks to a caretaker clause in the constitution.

FILE - Felix Tshisekedi (R), leader of Congolese m FILE - Felix Tshisekedi (R), leader of Congolese main opposition, the Union for Democracy and Social Progress (UDPS) party, flanked by Vital Kamerhe, leader of the (UNC) party, address a news conference in Nairobi, Kenya, Nov. 23, 2018. FILE - Felix Tshisekedi (R), leader of Congolese main opposition, the Union for Democracy and Social Progress (UDPS) party, flanked by Vital Kamerhe, leader of the (UNC) party, address a news conference in Nairobi, Kenya, Nov. 23, 2018.

His main opponent, Felix Tshisekedi, who has a promised a return to rule of law, was greeted by tens of thousands of supporters when he came back to Kinshasa last month to start his campaign.

But Kabila's opponents and supporters traded accusations of electoral violence on Monday as political tensions simmer less than three weeks before the presidential vote.

The pro-Kabila coalition said opposition supporters attacked a march over the weekend, injuring dozens while Tshisekedi's UDPS party said police detained more than 40 of his supporters in 48 hours.

Kabila's FCC coalition said "young delinquents, drug addicts who are UDPS supporters" attacked a march for Ramazani Shadary on Saturday in Mbuji Mayi in East Kasai province.

"We have 35 seriously injured and with fractures," an FCC statement said.

Local governor Alphonse Ngoyi Kasanji said on Monday there were 15 wounded treated at a local hospital.

A source at Tshisekedi's UDPS party said police had encircled its headquarters in Mbuji Mayi between Sunday night and Monday morning and had detained dozens of his supporters over the weekend.

"Around 20 of our activists were arrested on Saturday and are still in police custody. One of our parliamentary candidates is still reported missing," regional UDPS representative Denis Kalombo told AFP.

Vincent Ngoyi, a local official, said police had been deployed to UDPS headquarters in the region for "security reasons" because they were responsible for unrest on Saturday.