Seven small oil terminals and most of the shipping berths at Japan's northeastern ports remain closed more than two weeks after a devastating earthquake, government and industry officials said.

All 15 key ports damaged by the March 11 disaster have reopened for recovery efforts, Japan's transport ministry said on its website, but access was limited. As of Sunday, only 30 percent of the 208 shipping berths at the facilities were open.

A terminal operated by Mitsubishi Chemical was likely to stay shut for months, while inspections were being conducted at facilities run by Shin Etsu Chemical , Kashima Denkai, Kashima Kyobi and Kashima Oil.

JX Nippon Oil & Energy's terminal at the Port of Sendai and Onahama Petroleum's loading facility at Onahama were also closed and it was not known when operations would resume, maritime firm Inchcape Shipping Services said.

Despite ports reopening, seaborne trade was at a standstill in parts of northeast Japan as shipping companies divert their vessels away from the quake-crippled Fukushima nuclear plant due to radiation fears.

Engineers have been battling to control the six-reactor complex since the magnitude 9.0 earthquake and ensuing tsunami, which left more than 27,000 people dead or missing.

Fires, explosions and radiation leaks have repeatedly forced them to suspend work on averting a catastrophic meltdown at the plant, which lies 240 km (150 miles) north of Tokyo.

Radiation Fears
Radiation levels as of late Sunday in Tokyo Bay ports were below exposure levels the World Health Organisation considered normal, the ministry said.

"Currently, the level of radiation (at ports) in Tokyo City, Yokohama City, Kawasaki City, and Ichikawa City were shown to be at very safe levels to health," it said.

Most shipping companies have limited their exclusion zone from the nuclear plant to around 100 km, halting seaborne trade to the ports of Soma, Onahama and Sendai.

However, at least three container firms -- Germany's Hapag-Lloyd , Claus-Peter Offen and Hong Kong's Orient Overseas Container Line -- have widened their "no-go" area to more than double the industry norm to include Tokyo Bay.

Hapag-Lloyd has diverted a total of 16 vessels from the ports of Tokyo, Nagoya and Yokohama. A spokesman said the world's fifth-biggest container shipper would resume voyages to Nagoya this week.

Orient Overseas has omitted stops at the three ports for six of its shipping lines.

Some industry officials believed the three companies were overreacting and did not see other firms diverting their cargoes away from Tokyo.

China detected what it said were "abnormal" radiation levels on a Mitsui O.S.K. Lines container ship entering the port of Xiamen in eastern Fujian province last week, local media said.

The vessel, MOL Presence, was rejected, said shipbrokers, was on its way back to Japan and was expected to arrive at the port of Kobe on Wednesday.

Japan has hundreds of ports throughout its coastline with enough capacity to absorb vessels avoiding the northeast, industry officials said. (Reuters)