GREAT FALLS, Mont. (AP) - Federal drug agents are counting pain pills and reviewing medical records in an audit of clinics on Montana's Indian reservations, an audit launched in response to tribal concerns about abuse of prescription drugs.

"What we're hearing is that reservations have a horrendous drug problem, and we want to know where it's coming from, where the source is," said Jim Tilley, the resident agent in charge of the federal Drug Enforcement Agency's Billings office.

The probe began earlier this year and the agency has completed audits on the Blackfeet, Crow, Northern Cheyenne, Rocky Boy's and Fort Belknap reservations, DEA officials said.

Prescription drug abuse "has really suppressed our people," said Edwin Little Plume, the tribal health and social services chairman for the Blackfeet Tribal Business Council. He and others are concerned that painkillers are prescribed too freely at Indian Health Service clinics and are used to put off expensive surgeries.

The availability of prescription pain pills has fueled an illicit drug trade, they said.

"Our people who really do need the pain medication - they fear being bothered, being threatened for their meds," Little Plume said.

The audit's second phase, now under way, involves counting pills and reviewing medical records.

If problems are found, the DEA will give the IHS the opportunity to correct them.