Buses chartered by Ottawa have begun evacuating Canadians from the region of northern Japan where a desperate effort continues to prevent a meltdown at the Fukushima nuclear power plant.

The first bus is reported to have picked up 17 Canadians in Sendai on Friday and taken them 300 kilometres south to the embassy in Tokyo.

Foreign Affairs spokesperson Laura Markle couldn't confirm the exact number of Canadian passengers, but said a second bus would be leaving for Tokyo early Saturday.

Some of the 185 Canadians registered to be in the Sendai area have complained they weren't given enough advance notice of Ottawa's evacuation plans, and as a result missed the first bus.

Markle said that a Canadian consular official has been in Sendai all week working with local authorities and diplomats from other countries to locate Canadians.

She said at least 425 Canadians were registered in the broader area affected by the nuclear crisis, and that by Friday night approximately 90 per cent of them had been contacted.

Foreign Affairs staff in Ottawa were working with the Canadian embassy in Tokyo to get in touch with the rest, but Markle said that communications in the area devastated by the earthquake and tsunami remain difficult.

Ottawa has issued an advisory to Canadians in Japan to stay at least 80 kilometres away from the crippled power plant.