TOKYO (AFP) – Japan's foreign minister says the country is open for business and travel as domestic firms are recovering at "surprising speed" from the aftermath of the March 11 earthquake and tsunami.

"We promise all of you that Japan will reshape itself into a more dynamic country" through overcoming the calamity, Takeaki Matsumoto said in an article published by the International Herald Tribune on Saturday.

"Japan is and will remain open for business and travel," he said, pointing out that the World Health Organisation and others had said excessive travel restriction measures were unnecessary.

Governments around the world issued travel warnings and banned food imports after the March 11 quake and tsunami crippled a nuclear power plant which has leaked radiation in the world's worst atomic disaster since Chernobyl.

Matsumoto stressed that radiation levels in Tokyo never reached a level harmful to health and said food exports were safe as Japan had taken measures to prevent any shipments of contaminated produce.

"Naturally, such products will not be exported," he added.

Matsumoto said the government expected work at the crippled Fukushima nuclear plant would soon change from "emergency response phase to the planned and stable action phase."

The foreign minister also said manufacturers in worst-hit northeastern Japan were on track for a swift recovery.

"Many affected companies and factories are recovering at surprising speed, helped by innovative approaches to tackling the crisis," he said.

"Domestic and international supply chains are being reconnected," he added. "Japan's strength for manufacturing remains on full display."

Japan's industrial production plunged 15.3 percent from February to March, the sharpest drop since records began in 1953, after the disaster crippled supply chains and forced companies to shutter plants.