ADDIS ABABA (Reuters) – U.N. humanitarian chief John Holmes said on Wednesday there was international anxiety at a possible humanitarian crisis and accusations of rights abuses in Ethiopia’s Ogaden region.

Holmes went to the remote eastern region on Tuesday, the most high profile visit since Ogaden National Liberation Front (ONLF) rebels killed 74 people in an attack on an oil exploration field in April, provoking a government offensive.

Both sides say they have killed hundreds of the others’ fighters since then, and aid agencies say people in the region are suffering severe food and medical needs.

“There is the possibility of a very serious humanitarian crisis in the region as a consequence of the security situation,” Holmes said in carefully chosen words on a highly sensitive subject for Prime Minister Meles Zenawi’s government.

“What I was trying to do was symbolise by my visit the extent of international concern about the situation there and the depths of our concern to avert a serious humanitarian crisis there in the future.”

The Ogaden crisis has been largely overshadowed by other hot-spots in the region, including neighbouring Somalia and Sudan’s Darfur region.

Holmes reiterated calls for investigations into accusations of rights abuses. The ONLF says troops have been terrorising the people, while the government says it is the rebels, whom it calls terrorists backed by arch-enemy Eritrea, who are guilty.

“They are clearly serious allegations and they are coming from not just one source,” Holmes told a news conference.

“They need to be looked at carefully, they need to be taken seriously and, if possible, they need to be investigated openly and independently.”

Holmes said he had recommend such an investigation during meetings with officials including Meles.

“I did bring it up with the prime minister, he takes the issues seriously. He also recognises the damage that can be done with a counter-insurgency campaign,” he said.

“He said he would continue to take it seriously and make sure that didn’t happen as far as he could.”

(Reporting by Barry Malone)