A peacekeeper has been killed in a rebel ambush near the Central African Republic (CAR) town of Grimari, as deadly violence continues after contested elections last month.

Two other soldiers were injured when fighters from a coalition of rebel groups ambushed peacekeepers from Burundi and Bangladesh, the United Nations Mission in the country, MINUSCA, said in a statement.

The peacekeepers were conducting a security operation around Grimari, 200 km (120 miles) northeast of the capital, Bangui, he added.

The Burundian peacekeeper was killed in the second ambush, and two Bangladeshi peacekeepers were injured in the attacks and treated.

UN Secretary General Antonio Guterres has warned that the attacks “could constitute a war crime” and called for the perpetrators to be brought to justice, UN spokesman Stéphane Dujarric said.

The UN chief also reiterated “his deep concern at the continued efforts to destabilize armed groups across the country”, and called on all parties “to immediately end the violence and resolve their differences by peaceful means” .

The rebels are protesting against the re-election on December 27 of President Faustin-Archange Touadera. Following the announcement on January 4 of Touadera’s victory, the rebel coalition threatened to take the capital. They also seized towns in other parts of the country ahead of the vote.

The army is supported in its battle against the rebels by forces from Rwanda, Russia, France and the UN.

Security forces repelled attacks by rebels trying to capture Bangui on Wednesday after heavy fighting on the outskirts of the city amid a major escalation in violence that has rocked the country since last month. .

At least one Rwandan peacekeeper has been killed and another injured, according to the UN, while CAR Prime Minister Firmin Ngrebada said at least 30 rebels have also died.

Al Jazeera’s Malcolm Webb, reporting from Bangui, said the situation was “tense” before the expiration Sunday evening of a 48-hour ultimatum issued by the coalition of armed groups in government.

“Security sources say they also now have several cells here in the city in preparation for an attack,” Webb said.

“This precedes a Constitutional Court ruling due on Tuesday that will potentially reaffirm President Touadera’s post, making him for a second term.”

A sharp increase in violence in recent weeks has forced more than 60,000 people to flee the country, seeking refuge in Cameroon, the Democratic Republic of the Congo (DRC) and other neighboring countries, the agency said. United Nations for Refugees (UNHCR).

“The UN has reported widespread rights violations – kidnappings, torture, killings of civilians – and this has prompted many people to flee their homes,” Webb said. “People are always on the move; many do not take the risk to see what will happen.

The DRC has hosted the largest number of refugees – around 50,000 since December, including 10,000 who arrived on Wednesday when the rebel coalition staged attacks on the outskirts of the capital, according to UNHCR.

However, Cameroon has also seen an increase in the number of families, especially women and children, from the Central African Republic, he added.

“At the beginning, when they entered, they said it was a prevention movement, they were afraid because they remembered the violence they had suffered in 2013,” said Helen Ngoh Ada, spokesperson for the UNHCR.

“Lately, those who entered said that they had come mainly traumatized and that they had suffered some form of abuse, of human rights violations, and that is why they fled,” he said. she said in an interview with the Associated Press news agency.

People are allowed to cross the CAR into Cameroon, but the borders are closed to traders and trucks and supplies have not entered the Central African Republic for several days, Ngoh Ada said.

“This means that the livelihoods of the people of the Central African Republic are threatened, and this will be one of the reasons people move to Cameroon,” she added.

The mineral-rich CAR has faced deadly inter-religious and inter-communal fighting since 2013, when the Muslim-majority Seleka rebels seized power from former President François Bozizé after long claiming to be marginalized.

Resistance to the Seleka regime ultimately led to massive targets of Muslims, some beaten to death, mosques destroyed and tens of thousands of people driven from the capital in 2014.

Bozize has been accused of fueling the violence in recent weeks, which erupted after the Constitutional Court rejected his candidacy in December.