Nearly 90 percent of volunteer-staffed disaster relief operation centers in severely affected Iwate, Miyagi and Fukushima prefectures are limiting their intake of volunteers due in part to difficulty finding them accommodations, a Kyodo News survey showed Tuesday.

Some volunteer centers said they are shying away from accepting new workers as concerns grow over traffic jams ahead of the Golden Week holidays from late April to early May, according to the survey.

Of 65 operation centers, 56 are restricting the participation of volunteers, for example, by accepting only local residents.

"We have an oversupply of volunteers. It's even difficult to find accommodations for them," a volunteer center official said.

Increases in unpaid helpers "could cause confusion, including with the transportation situation" ahead of the long holiday season, as roads have already been jammed in parts of the areas stricken by the March 11 earthquake and tsunami, an official at another center said.

However, some observers criticize such moves, saying communities should make the most of the benefits offered by volunteers.In a separate move, the National Police Agency will start examining the mental conditions of about 10,500 officers, some of whom witnessed traumatic sights during rescue operations in the disaster-hit areas, in order to address their so-called critical incident stress.

The agency will send clinical psychotherapists next month to care for the officers in the three prefectures.