TOKYO — Japan’s government said the cost of the earthquake and tsunami that devastated the northeast could reach $309 billion, making it the world’s costliest natural disaster on record.

The extensive damage to housing, roads, utilities and businesses across seven prefectures, or states, has resulted in losses of between $198 billion and $309 billion, according to a Cabinet Office estimate today. That could drag the economic growth rate down by 0.5 percent this year.

The losses figure is considerably higher than other estimates. The World Bank on Monday said damage might reach $235 billion. Investment bank Goldman Sachs had estimated quake damage of as much as $200 billion.

If the government’s projection proves correct, it would top the overall losses from Hurricane Katrina. The 2005 megastorm that ravaged New Orleans and the surrounding region cost $125 billion, according to the Insurance Information Institute.

Japan’s estimate does not include the impact of power shortages triggered by damage to a nuclear power plant, so the final figure could be even higher. It also leaves out potential global repercussions.

“The aftermath of the tragic events in Japan will obviously alter the domestic economy,” said Takuji Aida, an economist at UBS Securities Japan, in a report. “However, Japan’s position in the global economy is such that there must also be some transmission of the shock to other parts of the world.”

The 9.0-magnitude quake and tsunami on March 11 laid waste to Japan’s northeastern coast, killing thousands of people and triggering a crisis at a nuclear power plant. Tens of thousands of people living near the plant were evacuated.

Utilities have imposed power rationing, many factories remain closed and key rail lines are impassable.