KIEV, July 18 - Ukraine may introduce restrictions onnumber of rail tanks in each train carrying chemical or hazardous materials following a recent crash that produced a toxic cloud, an official said Wednesday.

"I ordered the introduction of the restriction on a number of rail tanks and cars with hazardous cargo in one each train," Transportation Minister Mykola Rudkovskiy said. "For example, there will not be 15 tanks, but five or seven."