An army colonel deserted the Democratic Republic of Congo's government forces with at least 30 of his men to join the ranks of the M23 rebels stirring unrest in the country's east, the army said Tuesday.

Colonel Richard Bisamza left with 30 of his men in the early hours of Tuesday morning, Lieutenant Colonel Olivier Hamuli told AFP, adding that the decision was "not a surprise, given his ethnicity."

"His departure doesn't affect the army whatsoever. We aspire to have an army that isn't infiltrated by rats," Hamuli said.

Bisamza, an ethnic Tutsi, was supposed to travel from his base in the country's restive North Kivu province to the capital of Kinshasa for an appointment but instead fled to forests near the city to join the rebels.

Hamuli accused Bisamza of joining the ranks of the M23 based further south in DR Congo, closer to the borders with Rwanda -- ruled by fellow Tutsi Paul Kagame -- and Uganda.

Both countries are accused of supporting the rebellion by the UN, a claim they deny.

The Hutu and Tutsi are two large ethnic groups in eastern Africa with a long history of tensions between them.

In 1994, the Hutu majority in Rwanda killed an estimated 800,000 Tutsi in one of the worst genocides in history.

When Kagame overthrew the Hutu regime, hundreds of thousands of Hutu fled into the DRC, many of them perpetrators of the killings.

Their presence sparked a conflict drawing in several countries which ended in 2003, but militias from both ethnic groups have continued to wreak havoc in the mineral-rich eastern DRC.

The M23 is made up of Congolese Tutsi who were integrated into the army following a 2000 peace accord. They mutinied in April 2012 saying the accord was never fully respected.

M23 occupied regional capital Goma for 10 days in November before withdrawing under international pressure and in return for a dialogue with Kinshasa.

But after a truce of around two months, the army and the M23 resumed fighting on July 14.

A UN-sponsored radio station also reported the colonel Bisamaza's departure, but said he had defected with 60 men rather than 30.

The defection took place on the first day of work for Martin Kobler, the German diplomat who now heads a new UN peacekeeping force in DR Congo, which has a mandate to use "force" to disarm fighters.