WASHINGTON -- The U.S. government has warned domestic and international airlines that some terrorists are considering surgically implanting explosives into humans to carry out attacks, The Associated Press has learned.

There is no intelligence pointing to a specific plot, but the U.S. shared its concerns last week with executives at domestic and international carriers.

People traveling to the U.S. from overseas may experience additional screening at airports because of the threat, according to the Transportation Security Administration.

"These measures are designed to be unpredictable, so passengers should not expect to see the same activity at every international airport," TSA spokesman Nick Kimball said. "Measures may include interaction with passengers, in addition to the use of other screening methods such as pat-downs and the use of enhanced tools and technologies."

Placing explosives and explosive components inside humans to hide bombs and evade security measures is not a new idea. But there is new intelligence pointing to a fresh interest in using this tactic, a U.S. security official told the AP. The official spoke on condition of anonymity to discuss sensitive security information.

When the U.S. government receives information suggesting terror tactics that could threaten commercial aviation, the TSA alerts companies domestically and abroad. Last December, the U.S. received intelligence that al-Qaida's Yemen branch was considering hiding explosives inside insulated beverage containers to carry them on airplanes. That warning was shared with domestic and foreign airlines so that security could be on the lookout, even though there was no specific plot.

Airport security has increased markedly since the Sept. 11, 2001, terror attacks. But terrorists remain interested in attacking aviation and continue to adapt to the new security measures by trying to develop ways to circumvent them.