U.S. and Argentine authorities were investigating how the explosive made it onto the airplane in a college student's checked bag. The dynamite was discovered during a baggage inspection at Bush Intercontinental Airport shortly after a Continental Airlines flight landed Friday.

U.S. Immigration and Customs Enforcement spokeswoman Luisa Deason said the incident had no connection to terrorism. Houston Assistant Fire Chief Omero Longoria said the student, Howard Fish, 21, told authorities that he works in mining and often handles explosives.

The head of the Transportation Security Administration said the government is aware of the problem of looser security at international airports and is taking steps to fix it.

The head of the Transportation Security Administration said the government is aware of the problem of looser security at international airports and is taking steps to fix it. "We are focused on getting a base level of security around the world," Kip Hawley said in an interview taped to air Sunday on C-SPAN. "We'll put in additional measures where we think we need to."

Airline passengers traveling from U.S. and British airports were barred this month from bringing liquids and gels onto planes. The bans were instituted after British authorities said they had foiled a terrorist plot to use liquid explosives to blow up as many as 10 U.S.-bound airplanes.

There have been several attempts to destroy airplanes with bombs in checked luggage. In 1988, a bomb hidden in a checked bag exploded aboard Pan Am Flight 103 over Lockerbie, Scotland. All 259 people on the London-to-New York flight were killed, as were 11 on the ground.

Many countries use bomb-detection equipment for checked baggage that does not meet U.S. standards, according to a report last year by the Homeland Security Department.

"Checkpoint and checked baggage security measures have been radically improved in the U.S. since 9/11, and similar levels of improvements are essential in the rest of the world," the report said. "From the U.S. perspective, we are particularly concerned about security on flights inbound to our nation, but the worldwide fight against terrorism argues for making improvements universal."

It was not immediately clear what kind of bomb-screening procedures are used at Buenos Aires Airport in Argentina. Bob Hesselbein, national security committee chairman for the Air Line Pilots Association, said the equipment used in the USA would have detected a stick of dynamite.

"It will identify chemicals common to dynamite," Hesselbein said.

A United Nations group, the International Civil Aviation Organization, sets basic security standards for civil aviation worldwide. Those standards generally are lower than the standards for U.S. airports.

The organization plans to meet in Montreal in September to discuss raising the standards for international air security. Among issues to be discussed: the kinds of liquids that should be allowed on airliners.

Hesselbein recently attended the group's security conference in the Dominican Republic. "Airports in South and Central America are complaining they have to comply with TSA standards," Hesselbein said. "The greatest challenge they confront is not having the funds."

Hawley said that in the past few weeks he has talked with many of his counterparts from other countries, including Britain and the European Union, about tighter security standards.

Hawley said TSA inspectors visit international airports that have U.S.-bound flights and audit their security systems and procedures against the U.N. aviation organization's benchmarks.

In the past year, TSA inspectors determined that an airport on the Indonesian island of Bali and one in Haiti fell short of the standards. Airlines and airports were required to tell passengers traveling between the USA and the Bali and Haiti airports that there were security lapses. The requirement was lifted for Haiti in July.