WASHINGTON -- The United States has evidence Iraq has mobile laboratories to make chemical or biological weapons, the chairman of the Joint Chiefs of Staff said Friday.

Gen. Richard Myers also said the Pentagon probably would move a regional military headquarters to the Persian Gulf from their current base in Tampa, Fla.

Defense Secretary Donald H. Rumsfeld and other Bush administration officials have said that Iraq could have mobile weapons production labs, citing U.N. inspectors' reports that Iraq was trying to build them. Myers' comments at the National Press Club were the first suggesting the United States has evidence.

"There is evidence to support mobile production capability for chemical and biological weapons," Myers said. "It does not take a lot of space for some of this work to go on. It can be done in a very, very small location. And the fact that you can put it on wheels makes it a lot easier to hide from people that might be looking for it."

President Bush has asserted Iraq has chemical and biological weapons programs, a main reason, he asserts, for possible military action to remove from office Iraq's president, Saddam Hussein. Iraq claims such allegations are lies.

A mobile biological weapons production facility capable of making significant amounts of materiel could be set up in three to five tractor-trailers, according to a senior Pentagon official who spoke to reporters on condition of anonymity Friday.

Vice President Dick Cheney said Friday the administration also has classified information that shows Saddam is rebuilding his chemical, biological and nuclear weapons programs.

"There's an emerging threat here that must be addressed," Cheney said on radio host Rush Limbaugh's syndicated program.

Myers said Rumsfeld probably would decide to put a forward command center for the U.S. Central Command at a large air base in the Persian Gulf nation of Qatar. Central Command officials announced this week that about 600 core staff would move from the command's current headquarters in Tampa to Qatar in November for a training exercise.

Central Command oversees U.S. military operations in the Persian Gulf, east Africa and Central Asia, including Afghanistan and Iraq. Its commander, Gen. Tommy Franks, has recommended moving headquarters to the Persian Gulf.

The Qatar location is significant because the United States has been building a modern air operations center there as an alternative to one in Saudi Arabia.