A U.S. official says the United States has released illegal aliens who are violent criminals under a legal loophole resulting from recent Supreme Court rulings.

Testifying before a Senate Judiciary subcommittee, deputy assistant attorney general Jonathan Cohn says a number of violent criminals have been released under the legal loophole, and others are to be released soon.

"Among the aliens who will benefit are criminals who have murdered their wives, molested young children, and brutally raped several women," said Mr. Cohn.

Mr. Cohn says the loophole was created after the Supreme Court ruled in 2001 and again last year that criminal aliens could only be held in prison for six months pending deportation. If the alien's home country refused to repatriate the person, the individual must be released.

Mr. Cohn says Vietnam, Cuba and Somalia are among those countries that refuse to repatriate their own nationals. He urged Congress to pass legislation to close the legal loophole,keeping criminal aliens in prison indefinitely.

Victor Cerda, an official with the Homeland Security Department, says his division last year sent back 84,000 criminal aliens from the United States, but said some 400,000 remained as fugitives.

Mr. Cerda said 30 percent of illegal aliens fail to appear before an immigration judge, joining the ranks of fugitives. And he had little good news to report about those who do appear for their hearings:

"Of those that do appear for hearings, the other point of critical concern is that of those ordered removed, 80 to 85 percent fail to appear and comply with removal orders," said Mr. Cerda.

Republicans who control Congress are growing increasingly frustrated with what they perceive is little effort on the part of President Bush to address illegal immigration.

"He just does not get it," said Oklahoma Senator Tom Coburn. "The fact is, this country is very worried about our border."

Meanwhile, a dispute over immigration-related issues is delaying Senate passage of an emergency aid bill for military operations in Iraq and Afghanistan.

Senate leaders had hoped to schedule a vote on the 81 billion dollar legislation this week, but a number of lawmakers are insisting on attaching immigration-related amendments to the bill.

One of them would lift the cap on visas for seasonal workers, a provision introduced by Senator Barbara Mikulski, a Maryland Democrat, who says the legislation is needed for her state to adequately staff jobs in the seafood and tourism industry.

The House has already passed its version of the budget supplemental with its own immigration-related amendments. Once the Senate passes its legislation, differences in the two bills will have to be reconciled before a final measure is sent to President Bush for his signature.