"The Government of Rwanda has deployed force protection troops to the Central African Republic, under an existing bilateral agreement on defence," said a statement issued late Sunday.

"The deployment is in response to the targeting of the Rwanda Defence Force (RDF) contingent under the UN Peacekeeping force by rebels supported by (former president) Francois Bozize."

On Saturday, the Central African Republic's government accused Bozize of leading an attempted coup as tensions mount ahead of key presidential and legislative elections on Sunday.

A spokesman for the UN's MINUSCA peacekeeping force in CAR said Sunday that armed rebels that had been advancing on the capital Bangui had been pushed back.

Rwanda has been a main contributor to MINUSCA since it first deployed in 2014.

No details were given on when or how many Rwandan troops would be deployed, but the defence ministry said they would "also contribute to ensure a peaceful and secure general elections scheduled on Sunday".

MINUSCA's Rwandan contingent is notably in charge of the security of Central African Republic President Faustin-Archange Touadera and the presidential palace.

Bozize, who came to power in a coup in 2003 before himself being overthrown in 2013, had declared he was running in Sunday's vote and was considered Touadera's main rival.

But the 74-year-old was barred from running by the country's top court, ruling that an warrant was out for his arrest on charges including murder, arbitrary arrest and torture.

Touadera had previously said that Rwandan and Russian troops were on alert to help his country during the crisis.

Russia on Monday confirmed it had sent several hundred soldiers to the Central African Republic.