WASHINGTON, Jan 4: All travellers flying into the US from Pakistan, Afghanistan, Nigeria, Yemen, Saudi Arabia and nine other countries considered high risk  will be patted down and have carry-on luggage searched under new security procedures starting Monday.

In addition, all international passengers will see enhanced random screening, which may include pat-downs, explosive detection testing (swabbing of luggage) or body scans, the Transportation Security Administration (TSA)announced Sunday.

The new procedures follow the botched Christmas Day attempt to blow up a Detroit-bound US airliner blamed on a Nigerian man who US officials believe was trained by al-Qaida in Yemen. Pakistan's border with Afghanistan is also considered a key battleground in the US-led battle against al-Qaida and the Taliban.

Pakistan, Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Saudi Arabia, Somalia and Yemen are on the list as "other countries of interest". Cuba, Iran, Sudan and Syria are listed because they have long been identified as "state sponsors of terrorism" by the State Department.

This list was developed between Homeland Security and the State Department using the latest intelligence, NBC cited a senior federal official as saying.

"The new directive includes long-term, sustainable security measures developed in consultation with law enforcement officials and our domestic and international partners," the TSA said in a statement.

"TSA is mandating that every individual flying into the US from anywhere in the world travelling from or through nations that are state sponsors of terrorism or other countries of interest will be required to go through enhanced screening," it added.

"The directive also increases the use of enhanced screening technologies and mandates threat-based and random screening for passengers on US bound international flights."

The TSA said the ability to enforce the new security measures is the "result of extraordinary cooperation from our global aviation partners." Effective aviation security "must begin beyond our borders," it added.