Federal prison inmates will be limited to 300 minutes of telephone calls per month under a new policy launched yesterday by the U.S. Bureau of Prisons, which is hoping to crack down on abuse of phone privileges by some prisoners.

But critics say the new policy, which applies to more than 140,000 inmates in the federal prison system, will only further isolate criminals from family and friends, contributing to recidivism.

Previously, federal inmates could make unlimited telephone calls and pay for them from personal debit accounts, which include money earned in prison or sent by relatives. Each prisoner also was permitted 120 minutes per month in collect calls.

The new rules limit all telephone calls to 300 minutes per month, regardless of who pays the bill. The limit does not include calls made to defense attorneys or other legal advisers.

Traci Billingsley, a Bureau of Prisons spokeswoman, said that 75 percent of federal prisoners already use phones less than 300 minutes per month. Placing limits on the rest will help control attempts by some inmates to run drug rings or other criminal operations from prison, she said.

"There have been some instances in the past of inmates abusing the phones, using them for illegal or disruptive purposes," Billingsley said. "Telephone security has always been a concern of ours. We feel this will help us identify and limit any abuses."

But prisoners' rights advocates complain that the limit, which amounts to an average of 10 minutes per day, unduly restricts inmate access to family members, many of whom live hundreds or thousands of miles away and cannot afford regular visits.

In the District of Columbia, for example, some 8,000 prisoners will be in federal custody by Dec. 31 as part of the federal government's takeover of some functions previously performed by the District government. Federal prison officials say they will try to house inmates as close as possible to the District, but many already are incarcerated as far away as New Mexico.

"One of the things we know about recidivism is that close contact with family is one of the key factors in determining whether [released prisoners] will get into trouble again," said Alvin J. Bronstein, co-founder of the ACLU's National Prison Project. "This policy seems to run counter to that."

In a letter sent yesterday to Attorney General John D. Ashcroft, Citizens United for Rehabilitation of Errants (CURE), a prisoner advocacy group, argued that the new phone rules contradict a recent court settlement on telephone use, visiting privileges and other inmate policies.

CURE also maintains that security is not an issue, because all telephone calls in the nation's 98 federal prisons are routinely monitored or recorded. The group is considering litigation over the issue.

"Abuses can occur within 300 minutes," said Charles Sullivan, CURE's executive director. "There is nothing magic about 300 minutes. . . . These calls are being paid for by the prisoners. If they want to pay to talk to their family longer, we ought to let them."

The federal prisons recently completed installation of a new telephone system allowing use of the debit accounts, which use punch codes to keep track of prisoner calls and billing. Prisoners can use the system only to call 30 pre-approved telephone numbers. Calls to lawyers must be arranged separately and made from special phones that are not electronically monitored.

Calling costs for federal inmates range from 4 cents per minute for local calls to 85 cents per minute for calls outside North America and Mexico. A portion of the cost is pocketed by DynCorp, which runs the system. The rest pays for commissary expenses, cable television subscriptions and other inmate benefits, Billingsley said.

Alvin J. Bronstein, co-founder of the ACLU National Prison Project, is among those criticizing the new federal policy.