The Japanese government will help pay for the disposal of debris washing up on Canadian and American shores due to the catastrophic tsunami which hit the country last year, according to press reports from Tokyo.

Japan does not have to take care of such debris under international law, but in a report on Monday the English-language Nikkei newspaper said officials would announce a plan to provide assistance to the U.S. and Canada later this month.

According to Japan's English-language Kyodo News network, Chief Cabinet Secretary Osamu Fujimara confirmed a strategy for retrieving the debris could be drawn up before the end of September.

Beaches like landfills

Experts estimate more than 1.5 million tonnes of debris were swept out to sea when the tsunami struck on March 11, 2011.

The Kuroshio ocean current runs from Japan's east coast to North America, passing Vancouver Island and Haida Gwaii, where beaches have begun to resemble landfill sites because of the volume of debris washing up.

Volunteers in Tofino have been collecting tsunami debris washed ashore on Vancouver Island. (CBC)

While most of this debris consists of smaller items, including a motorcycle which volunteers are attempting to reunite with its Japanese owner, larger debris is already costing authorities millions of dollars to dispose of.

Earlier this year, the U.S. Coast Guard decided to sink an unmanned Japanese fishing boat after it appeared in March, floating about 275 kilometres off the coast of Haida Gwaii.

And in June, a 20-metre-long dock that had torn loose from a fishing port in northern Japan washed up on a beach in Oregon.

According to the Nikkei, Japan sees helping to pay for the cleanup as a "way of expressing appreciation for the outpouring of support following the disaster."