* Full restart of biggest power plant to take over a month
* Power shortages hampering clean-up operations
* Residents, businesses urged to reduce electricity usage (Recasts, adds detail)
TOKYO, Sept 11 (Reuters) - The biggest coal power station on Japan’s northern island of Hokkaido, hit by a devastating earthquake last week, will take weeks longer than thought to restart, a government minister said on Tuesday.
Clean-up operations continued after the magnitude 6.7 quake on Thursday, which left 44 people dead, knocked out power and damaged the only oil refinery on an island the size of Austria with a population of about 5.3 million.
Power shortages are hampering efforts to clear debris and restart factories and the government is calling on residents and businesses to reduce their consumption by about 20 percent.
Fully restarting Hokkaido Electric Power’s main power plant, the Tomato-Atsuma coal power station, will take more than a month, industry minister Hiroshige Seko told reporters. Previously he said it would take at least a week to restart.
Supplies will be tight until Friday, when the 200-megawatt Kyogoku No.2 pumped hydro-electric power unit is expected to come back online, Seko said. Rolling blackouts may have to be imposed from Thursday if supplies are not enough to meet projected demand, he added.
The power outage on Hokkaido was the worst to hit Japan since the aftermath of the March 2011 earthquake and tsunami and has exposed flaws in Japan’s electricity grid.
Supplies have been restored to almost all of Hokkaido’s 2.95 million power customers, Seko said.
All three units have sustained damage at the Tomato-Atsuma power plant, which normally supplies about half the island’s electricity.
The plant’s 350-megawatt (MW) No.1 unit is expected to start as early as the end of September, with the 600-MW No.2 unit not due back in operation until the middle of October at the earliest and the 700 MW No.4 unit only in November, Seko told reporters.
To help ease tight supplies, Hokkaido Electric has moved forward plans for restarting the 200-MW Kyogoku No.1 pumped hydro unit to Sept. 21, its spokesman told Reuters.
Idemitsu Kosan’s 150,000 barrels per day Hokkaido refinery sustained some damage to its refining facility from the quake and refining operations are still shut, the trade ministry said.
An Idemitsu Kosan company spokesman in Tokyo said preliminary checks indicated no major damage to the refinery and the company was preparing to restart the facility. He could not say when operations would resume.
Land product shipments of gasoline, kerosene and diesel from the refinery returned to normal on Tuesday, the company said.
Reporting by Yoshifumi Takemoto and Osamu Tsukimori; writing by Aaron Sheldrick; editing by Richard Pullin