New York: United States officials today (Nov 8) warned that al-Qaeda may be plotting to fly cargo planes to attack targets on American soil, announced shutting down of their three missions in Saudi Arabia because of security concerns and asked American journalists in Afghanistan to be on guard.

Officials cited new intelligence indicating that the threat was similar to the one that preceded the September 11, 2001 attacks on New York and Washington.

The most imminent threats were aimed at US targets overseas, but they said they could not rule out the possibility of an attack on US soil, officials were quoted as saying by the NBC Television network.

"The US intelligence community remains concerned about al-Qaeda's interest in carrying out attacks on us overseas. We also remain concerned about threats to the aviation industry and the use of cargo planes to carry out attacks on critical infrastructure," an official of the Homeland Security Department was quoted as saying.

The officials said the threat was strikingly similar to the plot in which 19 al-Qaeda operatives hijacked four US jetliners and flew three of them into the World Trade Center in New York and into the Pentagon a little more than two years ago.

Officials at the Homeland Security Department told the network that they had no immediate plans to raise the national threat level, which is currently at "yellow," or "elevated," but the department planned to issue an advisory to local law enforcement agencies, state homeland security officers and private industry, including airlines.

They also asked American journalists in Afghanistan to increase their "security posture" in view of the "credible" information that Taliban forces are actively searching American newspersons.

NBC Television network report came hours after the US had shut down its three missions in Saudi Arabia for at least three days, saying that they had intelligence that terrorists might have moved from planning to operational stage.

There was "credible" information that terrorists in Saudi Arabia were closer to carrying out attacks there.

The US Embassy in the Saudi capital, Riyadh, said in a warden message on its website on November 7 that the missions in Riyadh, Jiddah and Dhahran would close to assess their "security posture."

They will then advise the US community when the review is completed and when the missions plan to resume normal operations.

NBC quoted officials as saying al-Qaeda was also believed to be behind the threat to US installations in Saudi Arabia, as well as US 'commercial and maritime' installations in the region.

PTI