The accident occurred when the freight train traveling from the Central Asian country to Poland derailed outside Lvov, near the Polish border. Several cars caught fire, sending poisonous fumes over a large area.
Official reports said 49 people, including 15 children, were harmed by the fumes and 14 populated areas with a total of 11,000 residents were affected. During the cleanup operation, 18 emergency workers were also poisoned. Some 800 people were evacuated from the area.
The train will go to Kazakhstan via Russia. A spokesman for Russia's rail monopoly Russian Railways earlier said all required safety measures would be taken to escort the train along the route, bypassing populated areas in Russia.
The Ukrainian government said the accident was the country's worst man-made disaster since the 1986 Chernobyl tragedy. A special commission has been set up to investigate the accident, and criminal proceedings have been launched.
Ukrainian authorities cited the poor condition of the rail track as the main cause of the accident.
The Ukrainian government has allocated $2.8 million to eliminate the consequences of the disaster, the country's finance ministry said.
