GENEVA -- Myanmar has detained a dozen aid workers working for international organizations in the past month, with just one of them being released, a spokesman for the U.N. refugee agency said Friday.

Adrian Edwards said four Myanmar nationals working for the agency were arrested in June in areas of the country where there has been civil unrest, and three are still being held.

Two workers from the World Food Program and six from a non-U.N. group, Doctors Without Borders, had also been detained in several locations around Myanmar, and were still to be released, he added.

Edwards said that some of the detentions occurred in Rakhine state, an area of western Myanmar where a state of emergency was declared in June after ethnic clashes took place between Rohingyas and Rakhine Buddhists. The workers had been providing food, medical assistance and other help to displaced people.

He said the exact grounds on which they are being held remains unclear, and U.N. officials are seeking access to them.

Edwards told reporters in Geneva on Friday that discussions to free the staff are in "a delicate situation."

World Food Program spokeswoman Elisabeth Byrs said the U.N. resident co-ordinator Ashok Nigam, the top U.N. official in Myanmar, has reported to the Myanmar government that some U.N. staff members were detained for questioning by authorities in Rakhine state, and the U.N. is still trying to get access to these staff members.

She said the U.N. has decided not to release more information about the situation "out of concern for the privacy of its staff."

The refugee agency, meanwhile, says it has sent additional staff to Rakhine, where Myanmar authorities say more than 52,000 people have been displaced during riots.

In a statement Friday, the agency says it has been assessing the needs of people in 30 different places, and handed out blankets, temporary shelter, cooking sets and mosquito nets to 5,000 people.