LVIV, Ukraine (AFP) - Over 140 people have been hospitalised following a spill of highly toxic phosphorus in western Ukraine, officials said Thursday.

The number admitted to hospital after a train crash and fire Monday spewed toxic clouds into the air nearly doubled overnight Thursday to 143, of whom 43 were children, regional health ministry official Igor Gerych said.

But officials repeated assurances that there was no widespread danger to surrounding villages after a train derailed.

"The situation is stable and under control. No one is panicking," emergency situations ministry spokesman Pavlo Vasylenko told AFP.

Emergency workers on the site removed wreckage and covered the ground with flame retardant to avoid another flare-up, which could happen if the temperature goes above 30 degrees Celsius (86 degrees Fahrenheit), he said.

The accident took place when a train with 15 wagons of highly flammable yellow phosphorus derailed en route from Kazakhstan to Poland, where it was to be used to make fertiliser.

Deputy Prime Minister Olexander Kuzmuk, who on Tuesday compared the spill to the 1986 Chernobyl nuclear disaster, has since insisted there is no health risk to surrounding villages.

Kuzmuk appeared on local television in Lviv on Wednesday drinking local well water and eating a cucumber grown near the accident site.

A total of 11,000 people live in the area affected by the phosphorus spill.

Regional prosecutors are investigating whether the accident was caused by the violation of security regulations on phosphorus transport.