Akhir 07, 1432 H/ March 12, 2011, SPA -- Nordic nuclear safety authorities were Saturday monitoring developments following an explosion at a nuclear reactor in Japan, the day after a massive earthquake hit the Asian country. Finland and Sweden both operate nuclear reactors, according to dpa. The website of the Finnish Radiation and Nuclear Safety Authority (STUK) temporarily crashed Saturday due to the high volume of online visits. The site seized up when some 15,000 visitors tried to view it, compared to the normal average of 1,000-1,500 visitors, broadcaster YLE said, but the site was up and running later Saturday. In Helsinki, Paavo Arhinmaki, leader of the opposition Left Alliance, told a party conference that no further nuclear reactors should be built in Finland, citing events in Japan. Finland is set to hold general elections April 17. Last year, parliament approved building two new nuclear reactors. At present, it has four reactors, and a fifth is being built although that project has suffered from delays. In neighbouring Sweden, the Radiation Safety Authority set up a task force that was following events in Japan and experts from the agency were interviewed on national television and radio. Swedish nationals in Japan were advised to heed advise from Japanese authorities, the agency and Swedish Foreign Ministry said.