Washington: The United States has alerted international carriers, including those from India, flying directly into its territory, that terrorist groups might surgically implant bomb into human beings to carry out attacks.

"This is new intelligence about a possible technique that could be used, however there is nothing to indicate an imminent threat," a senior US security official said on condition of anonymity as he is not authorised to discuss intelligence information with the media.

The heightened communications and activities by the US, it is learnt, are in response to a potential threat, but there is no specific information about an imminent threat coming from a particular area.

"Such a threat is likely to come from overseas rather than domestically, but precautionary steps are being taken internationally and in the US," the official said.

It is understood that all countries including India with airports that have last-point-of-departure flights to the US have been alerted with the latest intelligence input gathered by the United States; which continues to be the prime target of the terrorists across the world, especially those based in Pakistan and Afghanistan.

Since the Indira Gandhi International Airport in New Delhi and the Chhatrapati Shivaji International Airport have flights having last-point-of-departure to the US, it is logical that tightened security might be experienced by passengers at these two Indian airports as a result of the latest terror alert.

The Transportation Security Administration (TSA), recently briefed air carriers and foreign partners to provide greater insights into recent intelligence indicating the continued interest of terrorists to target aviation, its spokesman Kawika Riley, said.

"Due to the significant advances in global aviation security in recent years, terrorist groups have repeatedly and publicly indicated interest in pursuing ways to further conceal explosives," he 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, the spokesman added.