New York: As the US remained on heightened alert in view of possible terrorist attacks, businesses and public institutions, including hospitals prepared to deal with any eventuality.

Federal Bureau of Investigation (FBI) and police officials briefed business leaders in packed meeting rooms in Washington on how to respond to terror strikes, while thousands of students practised emergency drills.

Hospitals were put in a state of readiness as government warned of a potential cyanide attack by terrorists. The New York City health department urged hospitals to increase supplies of sodium thiosulfate, the antidote to cyanide, and other such pharmaceutical agents in emergency rooms to meet with any chemical or biological threat.

Several hospitals have also instituted heightened security plans to respond to biological, chemical and other types of attacks involving treating large numbers of injuries.

The steps include locking down hospitals and shutting systems, reports said.

The alert asked emergency rooms in hospitals to prepare for an increase in patients with respiratory, neurological and skin conditions. Doctors were asked look out for any "unusual cluster of patients who may have attended the same public function".

People across the nation piled up food supplies, water and batteries, plastic sheeting and duct tapes being sold in major cities as soon as supplies were received by retailers.

The US government had suggested that people seal doors and windows using plastic sheeting duct tapes, in case of a biological or chemical attack.

Police were also patrolling the New York subway system with hand held detectors for chemical and biological agents, while the 14th Street Bridge and a metro station in Washington were shut temporarily after reports of suspicious packages.

In New York, 1,200 police persons have been assigned full time terrorism duties. The city has also increased the number of, what are called, 'Hercules Unites" – cops that patrol the streets in armoured vehicles and are stationed at strategic locations.

"We are up against very cunning and patient foe and we cannot underestimate them," said police commissioner Raymond Kelly.

The US military also announced that it had redeployed anti-aircraft missiles and other safeguards across the region. It revealed that it had activated ground-to-air missile systems, air defence radar and hand held missile launchers around Washington.

American authorities had indicated on February 11 that they were more worried about an attack than at any time since al-Qaida operatives attacked New York and Washington on September 11, 2001.

"This is the most specific (threat) we have seen," Central Investigative Agency (CIA) director George Tenaet had told the Senate committee meeting.

The release of an audiotape, believed to be the voice of al-Qaida chief Osama bin Laden on February 11 also heightened the alert.

PTI