NEW YORK (Reuters) - Disbelief and anxiety were written on the faces of staff at American International Group Inc as they grappled with the idea that their company, which was once the largest insurer in the world and one of the safest places to work, was struggling for its survival.

Workers at the company's lower Manhattan offices, one block from Wall Street, said there were more lunch deliveries than usual, as staff opted to stay inside rather than brave a phalanx of news reporters and cameras camped outside.

There was a bigger police presence than normal in the Wall Street area and security guards were double-checking IDs of everyone who came in or out of the AIG building.

Some workers at the 89-year-old institution were shocked that the company could find itself in a crisis like the ones at Lehman Brothers Holdings Inc, which just filed for bankruptcy protection after failing to find a rescuer, or Bear Stearns, acquired earlier this year in a "shotgun" merger.

"I came to this company because it was a big company, and big companies tend to stick around," said one male AIG employee who declined to give his name.

"There's a massive culture of uncertainty within the building," said a woman who has been in the insurance business for 20 years.

"I'll be the guy to turn out the lights and lock the door," joked a man who said he had a senior-level position at the company.

"I think the idea is to take a nap at my desk and be woken up when this is all over," another woman said.

One woman who went through the "Black Friday" stock market crash of 1987 played down the gravity of the current situation. "This is nothing compared to that," she said.