The amount of gas imported fell 4.8 percent in the first five months year-on-year to 1,680,758 terajoules (TJ). The average price paid at the border was 8,421.19 euros per TJ, up 22.7 percent.

Many continental European gas prices, including those recorded by BAFA, still track crude oil prices with a time lag of around six months.

Germany's gas comes mainly from Russia, which accounted for 35.3 percent of the total, followed by Norway and the Netherlands. Smaller volumes came from Britain and Denmark.

BAFA prices are used in the domestic market to track the cost of imports and to decide whether gas is competitive compared with other fuels.

Cheaper spot markets for gas have emerged at delivery hubs in Europe over the past 2-1/2 years.

These markets are expanding and increasingly overriding oil-indexed contracts in setting domestic gas prices, which has cut into incumbents' profit margins.