WASHINGTON - A hiring freeze has hit two federal crime-fighting agencies, and a third has slowed its recruitment efforts because of congressional budget delays.

Some officials say the delays threaten efforts to combat terrorism and violent crime.

The hiring crunch is largely the result of Congress' failure to approve the Justice Department's 2007 spending request. Lawmakers who oversee spending bills are now negotiating how much - if at all - to increase government spending. In the meantime, the agencies are being funded according to last year's budget levels.

Justice Department agencies feeling the squeeze are:

The Drug Enforcement Administration. A hiring freeze is expected to last through 2007, chief financial officer Frank Kalder said. Although more than 400 agents and support staff are expected to quit or retire this year, Kalder said the DEA might have to furlough additional employees if Congress does not give it about $95 million more than it did in 2006. Layoffs are not being considered.

The Bureau of Alcohol, Tobacco, Firearms and Explosives. Agency officials are "not hiring and are not back-filling open positions," spokeswoman Sheree Mixell said. The ATF says it needs $71 million more than last year just to sustain its workforce of 4,900.

The FBI. Recruiting and hiring have slowed since the budget year began Oct. 1. The agency has stopped advertising for job openings on its Web site.

Assistant FBI Director John Miller said the bureau still was hiring agents, linguists, analysts, and other high-priority employees.

"We're not in a hiring freeze," Miller said, "but for the time being, we are only filling those jobs that are essential to operations." The FBI employs about 12,600 agents and 18,000 support staff.

Nationally, rates of violent crime are on the rise after a three-year lull that began in 2001, according to FBI officials. In 2005, the latest annual statistics available, the number of murders, robberies, rapes and other violent crimes rose by 2.2 percent.

After the Sept. 11 attacks, the FBI shifted more than 500 agents from its traditional criminal investigations - including drug cases, bank robberies and white-collar crimes - to counterterrorism and counterintelligence programs that became the bureau's top priority. In response, the DEA hired about 500 additional agents between 2001 and 2006 to maintain the government's focus on drug investigations.

Without a budget in place, "the FBI and DOJ will not be able to maintain the operations tempo they've achieved since Sept. 11," said Sen. Barbara A. Mikulski (D., Md.), who chairs the Senate Appropriations panel that oversees Justice Department spending. She blamed Republicans for the funding delays.

"It means that they will not be able to hire and keep the agents that they have," Mikulski said. "This is an outrageous thing."

A spokeswoman for Sen. Richard C. Shelby (R., Ala.), who last year chaired that panel, declined to comment.