Japan's crippled Fukushima nuclear plant is not fully prepared to deal with violent storms, officials admitted Saturday, as the country braced for Typhoon Songda to hit.

The storm system was located about 30 kilometres (20 miles) southwest of Miyako-jima island, near Taiwan, as of 3:00 pm (0600 GMT), the Japan Meteorological Agency said.

The typhoon, packing gusts up to 216 kilometres (134 miles) per hour near its centre, is moving northeast and could hit Tokyo as early as Monday, the agency said.

It is not yet clear whether it will move towards the Fukushima Daiichi plant, more than 200 kilometres northeast of the capital.

But the typhoon has already brought heavy rain to the Fukushima region, prompting worries that runoff water may wash away radioactive materials from land into the Pacific Ocean.

Plant operator Tokyo Electric Power Co. (TEPCO) has been pouring synthetic resins over the complex to prevent radioactive deposits from being swept away by winds or rain.

A TEPCO spokesman said workers were mulling ways to continue their work even in storms.

"We are using a pump truck to pour water to (cool overheating) reactors. It is not yet clear how exactly we would conduct the work if strong typhoons hit the plant directly," he said.

Goshi Hosono, an aide of Prime Minister Naoto Kan, told a news conference Friday that more work had to be done to ensure that the approaching and future typhoons would not spread radioactive materials into the environment.