The Environment Ministry projects that 33,000 tons of tsunami debris will reach North America by next June, revising downward its earlier estimates.

After analyzing data including ocean currents and wind direction through June, debris swept away by the March 2011 tsunami was found to be moving at a slower pace across the Pacific than initially thought, the ministry reported Friday. In April, it forecast that 41,300 tons would reach North America by February.

The earlier study only predicted the amount of debris that would reach waters within 10 km of the North American shoreline, but the new calculations provide a more accurate projection by also predicting how many tons are likely to reach the continent's shores.

Around 290 tons are expected to reach North America by December, rising to 3,200 tons by February and 14,000 by April, the latest analysis showed. But the new estimates kept the total amount of debris washed away from the three hardest-hit prefectures -Iwate, Miyagi and Fukushima -unchanged at 1.33 million tons.

Ministry officials said the government does not intend to change its plan to provide $5 million (about ¥400 million) to the United States and 1 million Canadian dollars (¥80 million) to Ottawa to help cover cleanup costs.