OSAKA: Nissan Motor said Friday it would monitor all its vehicles made in Japan for radioactivity, amid international concern over efforts to avert a nuclear catastrophe at a stricken atomic plant. "We will continue to implement all appropriate measures to reassure the public that all products from our company remain within globally accepted safety standards," the company said in a statement. The testing will continue "until we are confident that any risk of contamination is completely removed," the automaker said. Attempts are being made by Japan's Self-Defence Forces to douse fuel rods and prevent a calamitous radiation release at the Fukushima No. 1 power station. Levels of radiation there have fluctuated wildly after the plant 250 kilometers (155 miles) northeast of Tokyo suffered critical damage from Japan's biggest ever earthquake last week and the devastating tsunami it unleashed. The government has set a 20-kilometer exclusion zone and told those living between it and 30 kilometers from the plant to stay indoors as hourly radiation levels in the some nearby areas spike. The twin disasters knocked out the cooling systems, sparking a series of explosions and fires. Authorities have since raced to keep the fuel rods inside reactors and containment pools submerged under water. If they are exposed to air, they could degrade further and emit even more dangerous radioactive material. Meanwhile, -Japan's major automakers are trying to find alternative parts suppliers to replace those knocked out of action by the colossal earthquake last week that has forced most of the country's car production to a halt. Analysts say production is likely to resume within the next few weeks, bouncing back from the Mar. 11 quake and tsunami which killed more than 6,000 people. Once parts are coming, automakers will be able to make up for much of the lost production in coming months, they say. What's likely to hurt in the longer run are logistical difficulties caused by destroyed roads, and limits on electricity use. Power stations have suffered damage including several nuclear power reactors that are beyond recovery - and leaking radiation in a still unfolding crisis. The yen's recent surge to record highs could also hamper automakers. Toyota Motor Corp., maker of the Prius hybrid and Lexus luxury models, has stopped production at auto assembly plants throughout Japan through next Tuesday. Among Japan's automakers, it will likely be least affected because most of its suppliers are located near the company's Nagoya headquarters, southwest of Tokyo, which is far from the disaster's epicenter in the northeast. Honda Motor Co. said its production halt at auto assembly plants in Japan will be extended by three days until March 23.