NEW YORK: Luxury hotels in the United States are rushing to step up security, as recent bombings reflect their vulnerability and popularity as terrorism targets.

Shortly after news spread that terrorists had launched a deadly siege on Mumbai, 75 police cars carrying 150 officers fanned out across Manhattan, lights flashing.

Their mission was to quickly shore up security with a show of force outside the Waldorf Astoria, New York Palace and other marquee hotels, reported The Mercury News in the US.

The response, though strictly precautionary, demonstrated that the deadly attack in India had far-reaching implications for police and private security officials in New York and other US cities.

'I think this could be a wake- up call,' said Mr Robert Grenier, a former CIA official with the Kroll Security Group.

Security experts say the business model for hotels demands openness and accessibility for visitors and guests, making total security almost impossible despite security barriers, metal detectors and high-tech surveillance gear.

That is why, experts say, hotels have been attacked by terrorists in Pakistan, Jordan, Afghanistan and now Mumbai, The Associated Press reported.

Mr Grenier said suspicions that the Mumbai terrorists may have had inside help point to the need for aggressive screening and monitoring of hotel staff. It is likely, he said, that the well-coordinated assault in India involved extensive reconnaissance - another lesson in the need for constant vigilance in spotting and confronting suspicious visitors.