In an accident that evoked memories of Chernobyl nuclear power plant disaster two decades ago, the derailment sparked a blaze in a cargo of yellow phosphorous, creating a cloud of gas that affected 14 villages in the former Soviet republic.
 
Oleksandr Kuzmuk, the deputy prime minister, who travelled to the area in the Lviv region, said: "A disaster has happened. After the Chernobyl catastrophe we are dealing with [another] case that can pose a real threat for our people.

"It is an extraordinary event, the consequences of which cannot be predicted."

He later backtracked on the remark, and other officials were at pains t o stress that the situation was under control and the danger minimal.

"A disaster has happened. After the Chernobyl catastrophe we are dealing with [another] case that can pose a real threat for our people"

Oleksandr Kuzmuk, deputy prime minister
"The cloud of a toxic gas dispersed and there is no threat for people's lives," said Ihor Krol, spokesman for the emergency situations ministry.

The train, en route from Kazakhstan to Poland, derailed near the city of Lviv, not far from the Polish border, and 15 of its 58 cars overturned, Krol said.

Six of them caught fire and the poison cloud spread over a 90 sq km area consisting of 14 villages, he said.

Rescuers extinguished the fire in the highly toxic substance, which can catch fire spontaneously on contact with air at temperatures higher than 40C. It can cause liver damage if consumed.

Advice to residents

Emergency workers sprinkled contaminated land with soda and sand and tried to cool off the cars, Krol said.

Residents were advised to stay inside, not to use water from wells, eat vegetables from their gardens or drink the milk produced by their cows. Of the 11,000 people living in the contaminated area, 815 were evacuated, Krol said.

Media reports said that other people had left the villages amid uncertainty about the effects of the accident.

On independent Channel 5 television, an elderly woman and a middle-aged man in one of the affected villages - neither identified - said that the authorities had not told them how to respond to the accident.

"Doctors did not come to our village. I only saw advice about what to do on TV," the woman said.

Chernobyl cover up

Concerns about the government response and instruction following
accidents still lingers from the 1986 explosion and fire at the Chernobyl plant in Ukraine, then a Soviet republic.

The Chernobyl plant saw the worst civilian
nuclear accident in the world [AP]
The Soviet government kept the world's worst civilian nuclear accident under wraps for days and played down the disaster long afterwards.

Mykola Rudkovsky, the transport minister, said a commission was working at the scene to determine the cause of the accident.

A criminal case was opened, which is standard practice in former Soviet republics, and Volodymyr Kozak, the state railway agency director, said sabotage had been ruled out as the cause.

Phosphorus compounds are chiefly used in fertilisers, although they are important components of pesticides, toothpaste, detergents as well as explosives and fireworks.