WASHINGTON -- Foreign-made buses that don't meet U.S. safety standards can drive across the nation's southern border to operate in this country because of gaps in safety laws intended to ensure those imported buses are safe, a federal safety official said Wednesday.

A 2005 Volvo bus involved in a Jan. 2 wreck near Victoria, Texas, that killed one man and injured several people was built to European safety standards. Under U.S. rules, imported buses must go through a registration process to ensure they meet U.S. safety standards.

But because this bus made daily trips between Houston and Monterrey, Mexico, it was considered to be involved in international trade and therefore wasn't required to have a manufacturer's plate stating it met U.S. standards, said Coleman Sachs, a National Highway Safety Administration official.

"What we've identified here is that there's a loophole big enough to drive a bus through, and they have been," said Debbie Hersman, an NTSB member. "They've been driving those buses across the U.S. border that don't comply with U.S. standards."

Meanwhile, cottage industries are emerging to help bus owners exploit loopholes, she said. A Dallas company, Green River Buses, helped the Texas bus register in California because Texas requires importation documents if registered first in Texas, Hersman said. Federal officials shut Green River down this summer.

Hersman said she watched inspections at Laredo for a couple of hours as part of the investigation of the Texas wreck. She said one bus that didn't meet the standards crossed into the U.S. while she was there.

The NTSB held a two-day hearing on the Texas wreck. The board will issue a report later on what caused the wreck and make safety recommendations to prevent similar future accidents.

The bus in the Texas wreck was owned by Capricorn Bus Lines Inc. of Houston and leased to International Charter Services Inc. Capricorn used International's U.S. Transportation Department charter number, a requirement for operating out of state.

Hersman said the testimony from the hearing showed the federal government is unable to identify buses at the U.S.-Mexico border that are not meeting Federal Motor Vehicle Safety Standards. She questioned whether anyone has authority to deal with such buses.

The Texas bus did not undergo a safety inspection at the border on the day it crashed because no state or federal safety officers were on duty when it arrived at the Laredo port of entry about 10:30 p.m. However, passengers went through immigration checks and border officers checked the bus for contraband.

Norm Littler, a vice president of the American Bus Association, said during a hearing break Wednesday that in 11 out of 60 fatal accidents in this country over 10 years, the bus was determined to be unsafe or illegal, according to federal reports. Those 11 accidents account for 129 of 229 fatalities over the decade.

"These guys are slipping through the cracks," he said. "We need to close these doors that are allowing these people to operate."

The federal government in 2002 proposed rules that would have required all motor carriers entering the U.S. to be certified they meet U.S. safety performance standards that apply to new vehicles.

Then-Transportation Secretary Norman Mineta announced the proposed rules March 14, 2002. The North American Free Trade Agreement opened U.S. roads to buses and trucks from Canada and Mexico. But Congress has repeatedly postponed their entry.

The proposed rules were withdrawn in 2005 and the Bush administration decided instead to ensure safety by checking for compliance with Federal Motor Carrier Safety regulations.

An inspector checking for compliance with the regulations would look at the brakes to check whether they are worn out or defective. But that inspector would not be equipped or trained to check performance standards such as whether the brakes meet stopping distance requirements or the seats meet flammability standards.

In 2007, a total 265,160 bus crossings were recorded at the southern border with Mexico and 136,400 at the northern border with Canada. A single bus could make multiple crossings. There were 13,500 inspections of buses on the southern border and 5,000 inspections on the northern border, said Larry Minor, an associate administrator for the Federal Motor Carrier Administration.