GENEVA (Reuters) - A special criminal court to try the worst crimes committed in the Central African Republic (CAR) is due to start its formal investigations next week, the United Nations’ deputy representative in the country said on Monday.

A U.N. report published last year said a litany of killings, rapes, mutilation, looting and torture committed by successive governments and armed groups in Central African Republic from 2003 to 2015 may constitute crimes against humanity.

Deadly clashes are back on the rise, state control is breaking down and inter-faith violence threatens to flare again. At least 26 people died in an attack by unidentified armed assailants on a church in the capital Bangui earlier this month.

“For us to stop this... horrible cycle (of revenge), the only way is to create a judiciary system that is credible, that is legitimate and that works, hence the special criminal court,” Najat Rochdi, U.N. humanitarian coordinator in Central African Republic and deputy special representative, told a news briefing in Geneva.

“The good news is that the special criminal court is going to be operational next week,” she said, adding that if it did not succeed, some people may return to seeking revenge.

The tribunal, which will be based in the CAR and composed of both national and international judges, will prosecute alleged war crimes and crimes against humanity.

Some 2,000 U.N. police are helping national authorities to arrest high-profile suspects, Rochdi said, adding: “Arrests are happening.” She gave no details of the arrests.

The United Nations is also supporting the CAR government in “developing a legitimate and credible and not corrupted regular judiciary system”, she added.

Repeated political crises in CAR have fueled conflict since 2003. Major violence erupted in 2013 when a mostly Muslim Seleka rebel coalition overthrew then-president Francois Bozize, prompting reprisals from Christian “anti-balaka” militias.

The International Criminal Court (ICC) has been investigating alleged war crimes and crimes against humanity in CAR since 2012.

The new court was agreed to in 2015, but it has taken time to finalize victim and witness protection, rules of procedure, and the swearing in of judicial police, Rochdi said.

Violence by armed groups is often aimed at wringing concessions from the government, including an amnesty, which Rochdi said would be a “disaster for the country”.

“The situation has worsened, one has to acknowledge it,” she said, citing an upsurge in violence in Bangui and elsewhere.