SHAKEN by Japan's devastating earthquake and tsunami, Chinese mainland's shares ended lower, along with other markets around the world, when the disaster struck last Friday.

But now, as Japan battles with its worst catastrophe since World War II, Chinese investors are trying to determine which companies listed on the mainland stand to win or lose from the disaster.

Oil companies such as PetroChina were among the first shares to suffer, at least in the immediate aftermath. But in a long run, they may be among the shares to benefit, analysts said.

Oil for April delivery ended its long-time rally over worsening unrest in Libya and fell below US$100 a barrel in New York after the 9.0-magnitude earthquake rocked Japan. It has since recovered a little to hover above around US$101.

Japan, the world's third-largest economy and crude user, has had to shut down five oil refineries affected by the quake.

The closedown is expected to decrease Japan's demand for oil in the short term and keep a lid on the rising prices seen in the weeks before the earthquake, China International Capital Corp said.

That assumes, of course, that unrest still bubbling in the Middle East doesn't get worse.

Japan has also had to close some of its nuclear power facilities because of damage caused by the earthquake and tsunami, and those flooded with seawater to cool down reactor rods will never reopen.

Japan gets about 20 percent of its power from nuclear sources, leaving a gap that will have to be filled as the nation begins the long and arduous task of reconstruction.

If investors are sufficiently patient, a rebound in the oil price is a certainty, CICC analysts said.

Coal, too, could be in demand. Japan gets about 30 percent of its power from coal-fired plants. Increased demand could benefit Chinese coal producers, CICC said.

On the downside, Japan's nuclear woes could cast a shadow over investor confidence in Chinese firms related to the nuclear power industry.

Companies such as Sufa Technology Industry Co, Shenzhen Woer Heat-Shrinkable Material Co and Shanghai Electric Group Co were hit hard in the past few days as worries about the safety of nuclear plants here and elsewhere in the world began to build.

Japan, a country with the world's most advanced nuclear power technology, is doing its best to avert possible meltdowns at its crippled reactors. Some investors are worried about China's ambitious plans to expand its own nuclear power industry and reduce its dependence on coal.

China sits between two major seismic belts - the Pacific Ring of Fire and the Alpide Belt and is also prone to earthquakes.

China's plan to get 15 percent of its power from non-fossil sources by 2020 calls for 40 atomic reactors to be operating by 2015, lifting the nation's nuclear power capacity to 40 gigawatts from the current 10.8 gigawatts.

As nuclear-power related firms lose their appeal for the moment, investors may turn their attention to companies that make radioactive-prevention products. Defense-equipment makers Jihua Group Co and Canal Scientific & Technological Co, radioactive measurement instrument maker Henan Hanwei Electronics Co, and iodine maker Inner Mongolia Lantai Industrial Co may see their stock prices jump, Industrial Securities said.

Chinese steel makers could also be big beneficiaries from the expected massive reconstruction in Japan, Changjiang Securities said.

Xinjiang Bayi Iron & Steel Co, Xinxing Ductile Iron Pipes Co, Sansteel Minguang Co Ltd Fujian and Shanghai's Baoshan Iron & Steel Co are rated as "buy" stocks by the Wuhan-based brokerage.

The earthquake has reportedly affected around 20 percent of Japanese steel production capacity. Three of that country's top steel makers halted operations as five of their factories hit by the catastrophe.

Japan exports 40 percent of its steel output, and most Japanese steel makers focus their production on steel plate for high-end products such as autos, Changjiang said.

Resumed operations at these steel plants will take time and require power support first. Even when operations return to normal, Japan will need a lot of steel material for construction projects, an area dominated by Chinese steel makers, said Liu Yuanrui, an analyst with Changjiang.

Chinese cement producers are in the same position as their steel counterparts. Zhang Yidong, an analyst with Industrial Securities, said he expects Japanese demand for cement could shoot up to 88.2 million tons by 2013, compared with an originally forecast 45 million tons for this year.

Mainland firms such as Anhui Conch Cement Co Ltd stand to be beneficiaries of reconstruction, Zhang said.

Investors should also be taking a close look at the electronics industry, analysts said.

Japan is a major electronics manufacturer, accounting for 13.9 percent of the global production of computers, consumer electronics and communications gear last year, according to research consultancy IHS iSuppli.

The quake and tsunami have destroyed vital infrastructure and hampered factory production, CICC said. China might be helping fill the gap.

Among the stocks to watch are electronic components maker Nantong Jianghai Capacitor Co, capacitor maker Xiamen Faratronic Co Ltd and IRICO Display Devices Co, CICC said.

In the automobile industry, the quake's aftermath will make it harder for Japanese car manufacturers to compete with other auto giants in China, the world's largest auto market.

Toyota, Nissan and Honda have already announced production suspensions at car plants in Japan, which means exports to China will be halted or delayed.

China accounts for 43 percent of Japanese cars exported to Asia, according to Changjiang Securities.

Any lapse in imports of Japanese cars will open the doors of opportunity to Chinese domestic manufacturers like SAIC Motor Corp and Dongfeng Yueda Kia. That could mean higher profits for Shanghai-listed SAIC and Jiangsu Yueda Investment Co, parent of the Dongfeng Yueda Kia joint venture.

Japanese makers had already been losing ground to German and South Korean counterparts in the Chinese market in recent years. The Japanese share of the market fell to 31 percent last year from 41 percent in 2008, Changjiang Securities said.

And finally there's the chemicals industry to consider. The quake-stricken area of Japan is home to many of the world's leading chemical firms, and prices of certain chemicals, such as methyl ethyl ketone, are expected to jump in global markets because of supply disruption.

Jiangsu Yangnong Chemical Co, Yantai Wanhua Polyurethanes Co, Zibo Qixiang Tengda Chemical Co and Befar Group Co could enjoy earnings growth on the back of price rises, Industrial Securities projected.