KIEV, Ukraine - Fire raced through deserted villages around the Chernobyl nuclear plant yesterday, sending wind-whipped radioactive particles skyward 10 years to the week after the world's worst nuclear accident.

Monitors flown in helicopters over the area of the fire recorded only a slight radiation increase, said Nikolai Komshensky, a spokesman for Ukraine's nuclear regulatory agency.

''We see no reason to be concerned now,'' he said.

Plant officials said the fire posed no danger to the Chernobyl plant, still in operation a decade after a reactor exploded, killing at least 30 people outright. Another 5 million people were exposed to radioactive fallout, mostly in Ukraine, Belarus and Russia.

No injuries were reported in the fire, which burned several acres before being put out after about 71/2 hours. It was not clear how much damage was done to the villages, officially off limits since the plant disaster.

Firefighters said the blaze was probably started by a cigarette dropped by one of the families visiting graves near the village of Tovsty Lis, about six miles northwest of the plant.

Old women sobbed and tried to shield grandchildren from the smoke as flames engulfed homes they were forced to abandon to radioactive contamination from the April 26, 1986, disaster.

The fire spread quickly through five villages in the 18-mile exclusion zone around the plant, carried by strong winds blowing toward Kiev and its 2.6 million residents. It burned pines and buildings in one of the areas most heavily contaminated with radioactive cesium.

The West has long pushed for Ukraine to close Chernobyl, but the energy-starved former Soviet republic says it needs the electricity and jobs the plant provides.

Dr. Fred Mettler, a University of New Mexico professor who led a 1990 study into the health hazards of the Chernobyl disaster, said the risks from radiation were minimal.

The cesium contamination from the 1986 accident mostly is in the soil, and not likely to be carried by smoke from burning buildings, Mettler said by telephone.

''I would be surprised if anybody would get enough of a lungful to significantly change their normal cancer risk,'' he said.

The environmental group Greenpeace, however, said fires can carry radioactive material to previously uncontaminated areas.

''This is clearly a danger to the health of people, and not only in Ukraine,'' spokesman Antony Frogatt said in Kiev.

Firefighters from Chernobyl's fire station rushed to the cluster of villages after the fire broke out.

Small forest fires are not uncommon in the exclusion zone around the plant. But Vasily Melnik, chief of the Kiev regional fire service, called yesterday's blaze the ''most significant'' since the 1986 accident.

The Group of Seven industrialized nations has pledged $3.1 billion to help close the plant by 2000, but the Western democracies set no date for delivering the aid at their summit last weekend despite an appeal from Ukrainian President Leonid Kuchma.

In Kiev, the Ukrainian capital, 19 activists from around the world were arrested Tuesday at a demonstration demanding the plant's immediate closure. Twelve were released. Among the seven still in custody were an American and a Dutchman, police said.

Only two of Chernobyl's four reactors are in operation. The No. 4 reactor is encased in a concrete sarcophagus that some experts say has deteriorated badly.