Bulgaria's national railway company will track its diesel locomotives via GPS from now on to combat increasing thefts of fuel, Transport Minister Alexander Tsvetkov said Friday.

"All 138 diesel locomotives will be equipped with GPS trackers by end-April," to prevent rising diesel fuel thefts from train engines, Tsvetkov told Trud daily newspaper.

Between 200 and 500 litres of fuel are syphoned off every month, he said.

The lost fuel over the past 20 years could fill up "a lake," the minister also told national BNT television, adding that railway workers were often involved in the thefts.

On Wednesday, the government already decided to tear up 133 kilometres (83 miles) of abandoned railway tracks, to save on money paid for guarding them from looters.

Bulgaria's ageing railways have been systematically stripped of tracks, signs and other metal equipment over the past few years, with looters -- usually from the poor Roma minority -- selling the material as scrap.

This has posed safety risks to passengers, with trains unable to travel at speeds higher than 100 kilometres (62 miles) per hour and having to slow down to 15-20 kilometres per hour on some sections.

Railway chief Pencho Popov recently said the country was planning to invest 813 million leva (415 million euros) in its rail system, which has some of the worst infrastructure in Europe.