Updated

U.N. inspectors spent three hours at the Iraqi customs department Sunday in their hunt for signs of weapons programs, while a short-circuit at the inspectors' headquarters in Baghdad brought Iraqi firefighters into the normally off-limits hotel.

Experts say Iraq has gone to great lengths to hide weapons of mass destruction, secreting programs in civilian areas and turning civilian materials to military uses. A search of customs department records could help inspectors determine what Iraq has imported that might help it develop banned weapons.

As usual, the inspectors left the customs department without speaking to reporters. They also went to a state-owned electronics factory and an engineering firm.

The inspectors also went to a chemical engineering design firm as well as two other locations in Baghdad: the Eyz Co. and the Salam Factory. The Eyz Co. produces electronic, communication and power distribution equipment. The Salam Factory produces communications equipment for civilian and military purposes.

Also Sunday, 12 more U.N. inspectors arrived in Baghdad, bringing to 110 the number of those who have worked in Iraq since inspections resumed Nov. 27 after a four-year break.

The customs department was one of the more unusual stops for the inspectors looking for biological, chemical or nuclear arms. Previously, the inspectors visited a variety of sites, from al-Tuwaitha, Iraq's major nuclear research center, to a factory Iraq says produces baby milk but the United States claimed made biological weapons. The inspectors also have explored one of President Saddam Hussein's palaces.

A day earlier, in response to a key U.N. demand, Iraq gave the inspectors a list of more than 500 scientists who have worked on nuclear, chemical, biological and missile programs.

U.N. weapons sleuths hope that the list, written in Arabic, will open more avenues to learning about Iraq's suspected weapons of mass destruction programs.

Meanwhile Sunday, an electrical short circuit meant Iraqis were allowed into a place usually off-limits -- the inspectors' headquarters.

U.N. spokesman Hiro Ueki said a small fire from the short circuit broke out on the ground floor at about 7 a.m. but was extinguished quickly.

"It did not affect the premises for inspectors, which are located on the top floor," Ueki said.

An Iraqi civil defense official, who refused to give his name, said the short circuit was in the computer room. Three Iraqi fire engines and a police car raced to the hotel that has been converted into offices and living quarters for inspectors on the outskirts of Baghdad. Iraqi firefighters left the hotel carrying scorched papers and small pieces of twisted metal.

Security has been tight at the three-story Canal Hotel. Cleaning and maintenance crews from Cyprus, where the inspectors have another base, were flown in to ensure Iraqi access to the building would be minimal. The building was swept for electronic listening devices before the inspectors moved in.

While strenuously denying it possesses weapons of mass destruction, Iraq so far has complied with most Security Council requirements, including allowing the inspectors in and giving them access to sites, delivering a declaration on the state of its weapons programs, and handing over Saturday's list of scientists.

Under the world body's tough new sanctions regime, U.N. inspectors are allowed to speak to Iraqi scientists in private and even take them outside the country for interviews -- requirements Washington hopes will prompt scientists to reveal hidden arms programs.

Inspectors have spoken with engineers and experts at sites they have searched and have reported two formal interviews with Iraqi scientists, both on nuclear programs.

Both scientists told reporters they wanted to be interviewed with Iraqi officials in attendance and were. Iraqi officials have said they do not believe it is necessary for scientists to be taken out of the country but will allow it if a scientist consents.

If Iraq convinces inspectors it is not hiding weapons of mass destruction, it might avoid a U.S. military strike. But inspectors have said Iraq's weapons declaration is wanting, and America has dismissed it as a lie.