After Russia's decision to stop supplying Gazprom Germania, Berlin has to buy an extra 10 million cubic meters of natural gas per day.
Russia's sanctions against Gazprom Germania and its subsidiaries could cost German taxpayers and gas users an extra $5.4 billion (5 billion euros) a year to pay for replacement gas.
The estimated cost was reported by German Welt am Sonntag weekly on Sunday, citing industry representatives.
In May, Russia decided to stop supplying Gazprom Germania, which had been the German subsidiary of Gazprom, after Berlin put the company under trustee management due to Russia's offensive in Ukraine.
Since then, the Bundesnetzagentur energy regulator, acting as trustee, has had to buy replacement gas on the market to fulfil supply contracts with German municipal utilities and regional suppliers.
The economy ministry estimates an extra 10 million cubic metres per day are required, said a ministry spokesperson, confirming a number cited by the newspaper.
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'Additional costs to be passed on to customers'
"The quantities are procured on the market and at market prices. No information can be given on the exact amounts due to commercial confidentiality," said the ministry spokesperson in an emailed response.
Welt am Sonntag said the current cost would be about $3.75 billion (3.5 billion euros) a year and that further costs could arise from the filling of the Rehden natural gas storage facility.
Economy Minister Robert Habeck had ordered the facility to be filled on Wednesday.
The paper also said the additional costs would be passed on to energy suppliers and end customers in the form of a gas levy from October.
The ministry spokesperson said supplies were not at risk.