Oct. 31 (Bloomberg) — Oil prices at $100 a barrel in New York would not be sustainable given the state of the global economy, according to the former executive director of the International Energy Agency.

Oil stockpiles may not need to be tapped as slow growth limits global demand from most economies, Nobuo Tanaka, who left his post at the Paris-based energy agency’s helm in August, said today at a conference in Singapore.

Crude for December delivery dropped 0.3 percent to $93.02 a barrel today in electronic trading on the New York Mercantile Exchange. Brent oil was at $109.40 a barrel, down 0.5 percent, on the ICE Futures Europe exchange in London.

Demand could increase if Japan doesn’t resume atomic reactors that have been off line since the March 11 earthquake and tsunami, he said. A glut of natural gas may also disappear as Japan boosts imports for thermal power generation to make up for the lost nuclear capacity, Tanaka said after his speech.

The debate over whether to start Japan’s reactors is “chaotic,” with no firm time estimates, Tanaka said. “Logically speaking, it should restart early next year.”

Japan’s liquefied natural gas imports rose 11 percent to 6.7 million metric tons in September from a year earlier as nuclear output plunged in the wake of the Fukushima disaster, the nation’s finance ministry said this month. LNG demand may grow to 97.4 million tons by 2020, compared with 70 million tons last year, according to Hong Kong-based analysts at Sanford C. Bernstein & Co.

–Editors: Mike Anderson, Alexander Kwiatkowski.

To contact the reporter on this story: Yee Kai Pin in Singapore at kyee13@bloomberg.net

To contact the editor responsible for this story: Alexander Kwiatkowski at akwiatkowsk2@bloomberg.net