Washington ? Evidence that doctors are at the heart of a British terrorist plot has foreign-born physicians in the U.S. on edge and wondering whether already stringent immigration security will get even tougher.

Six physicians are among eight suspects in the failed terror attacks, including one from Iraq, one from Jordan, two from India and a man identified by hospital staff as being from Lebanon.

“We’re hoping and praying these physicians are cleared and that they’ve done no harm,” said Dr. Subramaniam Balasubramaniam, past president of the American Association of Physicians of Indian Origin.

The attacks led British Prime Minister Gordon Brown to order a review of Britain’s medical recruiting policies, which for years had been crafted to help fill a doctor shortage.

Officials have not called for such a review in the U.S., where foreign doctors face not only difficult licensing requirements but lengthy background checks and security interviews.

Still, doctors and immigration lawyers are bracing for possible fallout.

“This is going to complicate matters,” Balasubramaniam said. “I’m sure Homeland Security will have a microscopic examination of physicians coming from abroad. I expect them to do that.”

Medical practitioners normally are licensed at the state level. The federal government does not track how many foreign-born doctors are in the U.S. at any given time, but George Washington University researcher Fitzhugh Mullan estimates there are more than 130,000 currently practicing in the U.S.

India has the most, with more than 40,000 doctors, followed by the Philippines with nearly 18,000 and Pakistan with nearly 10,000, according to Mullan’s research.

Foreign doctors usually come to the United States on temporary visas enabling them to complete their residency and take U.S. medical tests.

Before they arrive, their names are checked against FBI and intelligence databases. They are interviewed by State Department officials. They are interviewed again by customs agents in the United States and, under a pilot program being expanded in all airports, all foreign visitors are fingerprinted and photographed.

“These recent events in many respects validate the intense scrutiny we’ve placed on foreign nationals coming into the United States,” said Homeland Security spokesman Russ Knocke.

Under federal law, after doctors’ residence work is complete, they must then return to their home countries for two years before they can apply for a work visa or green card to return to the United States. Then they must pass through the security process again.

A recent Government Accountability Office report criticized U.S. officials for not tracking where those physicians are placed – leaving some areas with no help and others with too much. Plans to fix the problem have not yet been implemented.