This is the second time China has asked for word of the situation since the 11 March accident.
Chinese news agency Xinhua reported that Premier Wen Jiabao called on Tokyo to "promptly and accurately inform China" about developments.
The Japanese Foreign Ministry responded by saying that Prime Minister Naoto Kan in turn told Wen that Japan would continue to provide China and the rest of the international community with "information with utmost transparency".
The accident at the Fukushima Daiichi nuclear plant was triggered by a massive earthquake and tsunami, and Japan continues to be rocked by strong aftershocks.
Chinese consumers briefly flocked to supermarkets to buy salt in the mistaken belief that the iodine it contained could profectect them from adverse radiation effects. China, which is 1,200 kilometres from Japan, has already detected low levels or radiation in the air. Radiation has also been found on spinach grown in the north, including in Beijing.
Although the Chinese government has announced that the contamination is minimal, they have taken preventative measures and have banned Japanese food imports from the 12 prefectures near the Fukushima plant.