PRAGUE, JULY 19 -- News of cuts in Soviet oil deliveries to Eastern Europe has set off panic buying in the region this week, with tens of thousands of motorists in Czechoslovakia and Bulgaria waiting in six-hour lines to buy gasoline and other petroleum products.

The crisis appears to have hit Bulgaria the hardest. The state airline, Balkan Air, announced it would stop selling tickets for domestic flights after July 22 in anticipation of jet fuel shortages.

In Czechoslovakia, a 50 percent increase in the price of gasoline was imposed by the government on Wednesday in an effort to slow demand and reduce the number of motorists waiting in lines. But some cab drivers said that one-hour waiting periods were common today, even at pumps reserved for taxis and police cars.

In Hungary, the state news agency announced that Soviet oil imports for the end of July would be cut back by 190,000 tons. Hungary has a large supply of gasoline reserves, however, and the news agency reported no panic buying brought on by the announcement.

To some Czechoslovaks waiting at gas stations, the trouble was an unwelcome reminder of sacrifices that lie ahead as the country converts to a free-market economy and restructures or ends unprofitable trading arrangements with the Soviet Union.

The fuel shortages are a result of the mounting problems plaguing the dilapidated Soviet oil industry, including several major oil-field accidents. In the past six months, 1,132 pipeline ruptures have been reported in the Soviet Union -- a 15 percent increase over the same period last year.

All former East Bloc countries except Romania are heavily dependent on the Soviet Union for oil supplies. Oil deliveries to the region were cut back in January, but the Soviet Union had promised to supply the rest later in the year. The first strong indication that the Soviet Union would not make up the oil shortages came last week in a speech by Soviet Prime Minister Nikolai Ryzhkov.

Czechoslovak Finance Minister Vaclav Klaus told reporters this week that Soviet oil deliveries to the country were down by as much as a third this year. He said Czechoslovakia had been trying to find alternative gasoline suppliers in world markets but had done so quietly for fear of sending the wrong message to the Soviets.

Klaus, the leading advocate here of a rapid transition to a free-market economy, has used the gasoline crisis to further his proposals. Confronted with growing gas lines early this week, Klaus persuaded the government to use market demand to dampen consumption and force higher prices rather than imposing rationing.

In Bulgaria, supply problems are being exacerbated by the government's failure to eliminate communist-era subsidies that kept the price of gasoline artificially low.

Bulgaria absorbed a 10 percent Soviet oil cutback at the end of 1989, and an additional reduction was announced this month. But government figures show that gasoline consumption jumped 150 percent in the first half of this year, at the same time as industrial production was dropping.

Economists blame the surge in consumption on Bulgarians who have taken advantage of loosened travel restrictions by buying large quantities of cheap Bulgarian gasoline and reselling it in neighboring Greece and Yugoslavia.