Scientists kept close watch Tuesday on radiation levels from a Ukrainian nuclear power plant accident, but experts said Western Europeans face no immediate threat from the cloud of fallout drifting from the Soviet Union.
Unusually high radiation levels were reported Tuesday in Poland, Denmark, Finland, Norway, Sweden, Belgium and parts of West Germany.
Experts said they were carefully monitoring the situation, but radiation levels had not risen to levels that would pose a danger to humans.
Polish officials announced plans Tuesday to give children special anti-radiation drugs and to dump milk from grass-fed cows because of possible contamination. They said the level of potentially hazardous radioactive iodine was increasing over northeastern Poland but posed no immediate health threat.
The Swedish radiation institute said milk was being checked nationwide for abnormal iodine levels. The measure was a precaution, it said, adding there was no health hazard.
The radiation cloud was moving north on a polar route, which the U.S. Environmental Protection Agency said could take it to the West Coast of the United States in five or six days.
''We understand there is no danger to the United States,'' White House spokesman Larry Speakes said.
Because of overnight rains, radioactivity in the air in Sweden had dropped from Monday's levels but ground radiation was up in some areas, the Swedish nuclear inspection authority said.
Officials said the radiation, although more than 100 times higher than normal levels in some areas, was not enough to be harmful to humans.
Jan Olof Sneihs, spokesman for the Swedish radiation institute, said milk was being checked nationwide for abnormal iodine levels.
In Bonn, a West German authority on nuclear safety described the incident as a ''super accident'' -- the biggest that could take place.
Professor Adolf Birkhofer, head of the German Society for Reactor Safety, said in a newspaper interview there was immediate danger for people living within 6 miles of the reactor.
''This was different from a simple accident that could no longer be mastered,'' he told the Bild newspaper. ''According to the information available to me it was a super accident ... the biggest accident that can be imagined.''
A weather forecast said any further radioactive leaks from the giant Chernobyl plant 1,000 miles south of Stockholm, Sweden, would likely drift southwest to Poland and Czechoslovakia.
One Soviet diplomat called it the world's worst nuclear accident.
American experts agree many Soviet plants lack reactor containment structures to keep radiation from escaping during a mishap. Without containment vessels, ''the consequences could be catastrophic'' in the immediate area of the accident, said U.S. expert Paul Leventhal of the non-profit Nuclear Control Institute.
Other experts said contamination could ''extend for tens of miles in all directions'' and affect the area for ''decades to come.''
The Soviets sought aid from Sweden and a West German private nuclear panel in fighting a fire at the power plant 80 miles north of Kiev, a city of 2.3 million in the western Soviet Union. The West German and U.S. governments have offered to help.
Swedish and West German officials said Soviet diplomats asked for advice on fighting a graphite fire in a reactor. Experts said graphite burns like coal.
The Swedish radiation institute warned Soviet-bound tourists to stay at least 60 miles away from the ill-fated nuclear plant and to avoid the area between Kiev and the Baltic coast.
A slight increase in radioactivity was measured Tuesday by the Belgian meteorological institute, but officials were uncertain if it could be attributed to the nuclear accident in the Soviet Union or have occurred naturally.
Polish television told viewers in a morning news broadcast Tuesday there was no danger, but a government commission had been set up to evaluate the situation.
''As a result of it (the accident) yesterday, a radioactive cloud passed above Poland's northeastern areas at a high altitude,'' newscasters said. ''Measurements taken in Poland show that the radiation levels do not endanger the health of the population.''