PHOENIX — Maricopa County Sheriff Joe Arpaio, who gained notoriety for putting inmates on chain gangs and issuing them striped uniforms and pink underwear, has now ordered all undocumented immigrants currently in jail to register for the draft.

About 500 undocumented immigrants housed in the Phoenix-area county's jail system have not complied with a 1980 federal law that requires all men between the ages of 18 and 26 to register for the draft, regardless of their immigration status, Arpaio said.

"I can't say that I've ever heard anything like this, but we do appreciate any effort toward compliance," said Dan Amon, a spokesman for the Selective Service System in Washington, D.C.

He said Arpaio may be doing the undocumented immigrants a favor by ordering them to register, because Selective Service is tied to a number of benefits, including citizenship.

If they want to legalize their immigration status, the first thing they would be asked is whether they are registered for the draft, Amon said.

The United States hasn't had a draft since 1973. Registration was reinstated in 1980, and the law still requires that males who are U.S. citizens or resident aliens register within 30 days of their 18th birthdays.