The usual cheery morning banter gave way to subdued pleasantries and hugging as a resilient band of oil dealers returned to the trading floor of the New York Mercantile Exchange (NYMEX) yesterday.

Dealers were shipped in by special ferries to the world's largest commodity exchange, shut since Tuesday when two hijacked planes destroyed the twin towers at the nearby World Trade Center.

"It's very somber here," said Gerald Samuels, a trader at ARB Oil, who added the number of traders on the floor was much reduced.

A brief memorial ceremony attended by New York Governor George Pataki and U.S. Senator Hillary Clinton of New York further deepened the gloomy atmosphere at the trading floor.

Though most NYMEX energy trading personnel were accounted for when trading began, some NYMEX traders who have friends or colleagues who worked in the nearby World Trade Center were still too shaken to recount last week's events.

"There's nothing I can say at the moment, we want to reflect on all of this," said one trader.

Volumes were thin as trading in the open outcry system resumed at 11:45am (1545 GMT) and will close at 2pm (1800 GMT). Crude prices fell 46 cents to $29.07 a barrel by 1:30pm (1730 GMT) as wider economic gloom overshadowed concerned over oil supply safety.

Many oil trading firms were operating normally. with some using back-up computer systems that they built after the 1993 terrorist car bomb attack on the World Trade Center in which six people were killed, 1,000 injured and caused $300 million in damage.

"We're resuming trading and we'll go through the motions, and everybody's trying to hold on, out of respect to those who are not here," said Dominic Cagliotti, an oil trading veteran at ABN-Amro.

There were worries about telephone lines and fax machines, many of which were disabled when the twin towers and a nearby building in the WTC complex collapsed.

"We've got a number of telephone lines not working, but I think we'll manage through the day," said a trader from Sterling Commodities, whose offices are right on One North End Avenue, which houses the NYMEX trading floor and offices.