The 300 megawatt Qinshan 1 plant in Zhejiang province was shut down last July after what one nuclear safety official described as a "welding problem".

The problem caused bolts holding guide pipes to the main body of the reactor to fall off under strong water pressure, the official is quoted as saying.

Nuclear ambitions

He added that the plant would begin producing electricity again next month following repairs.

Nuclear power is seen as the key to China's economic development

It is the first time Chinese officials have given details of the accident at the plant 100 kilometres (62 miles) south of Shanghai.

China has only two operational commercial nuclear power stations but has an ambitious nuclear power construction programme in what is an increasingly energy hungry country.

At present China relies heavily on coal and oil fired power stations but the government regards nuclear power as a cleaner alternative.

The Qinshan plant was the first to have been designed and constructed using domestic resources.

No leak

Officials say no one was hurt in last year's accident at the Qinshan plant and there was no leak of radiation.

However newspaper reports in neighbouring Japan have expressed alarm at the delay in reporting the incident.

The national Asahi Shimbun said on Monday that the accident showed "problems in technical standards and disclosure of information as China and other Asian nations are trying to speed up their development of nuclear power plants".

Tokyo 'informed'

A Japanese Government official has confirmed that Beijing informed authorities in Tokyo at the time of the accident "on condition it should not be made public" but refused to give details.

Under a bilateral agreement China and Japan exchange information on problems at nuclear reactors.

The Japanese official said that Chinese nuclear safety authorities had determined that the magnitude of the trouble was lower than Level Two on the scale of eight set by the International Atomic Enegy Agency (IAEA).