TOKYO (AFP) -- Japanese motorists are paying more at the pump for their gasoline (petrol) now than at any time since February 1991 during the first Gulf War, a survey showed Monday.

The retail price of regular gasoline in Japan rose to an average of 135 yen (1.21 dollars) per liter (0.26 gallons) on May 1, up four yen from a week earlier, the Oil Information Center said.

Gasoline prices are rising in many countries around the world as refiners struggle to keep up with burgeoning demand and after crude oil prices soared to record levels in part due to worries over Iran's nuclear program.

The government voiced concern about the impact of soaring crude oil prices on the Japanese economy.

"The recent rise in oil prices cannot help but affect firms and households," Vice Economy, Trade and Industry Minister Hideji Sugiyama told a news conference, adding that the government would closely monitor oil price moves.

The ministry plans to release next week the result of an urgent survey on the impact of rising oil prices on the nation's small businesses, Sugiyama said.

According to a recent survey carried out by the ministry, some 40 percent of Japanese firms which rely on oil as an input for their production said soaring crude costs were putting "great pressure" on their earnings.