Russia has scrapped a Saturday deadline to resume flows via a major gas supply route to Germany, deepening Europe's difficulties in securing winter fuel, after saying it had found faults in the Nord Stream 1 pipeline during maintenance.

Nord Stream 1, which runs under the Baltic Sea, had been due to resume operating at 0100 GMT on Saturday after a three-day halt for maintenance.

But Gazprom, the state-controlled firm with a monopoly on Russian gas exports via pipeline, said on Friday it could not safely restart deliveries until it had fixed an oil leak found in a vital turbine. It did not give a new time frame.

However, Siemens Energy, which normally services Nord Stream 1 turbines, said such a leak should not stop the pipeline from operating. It also said the Portovaya compressor station, where the leak was discovered, has other turbines for Nord Stream to keep operating. 

"Such leaks do not normally affect the operation of a turbine and can be sealed on site. It is a routine procedure within the scope of maintenance work," the company said.

The pipeline has been shut down for the past three days for what Gazprom described as maintenance work.

The news comes amid growing fears that families in the EU will not be able to afford the cost of heating this winter.

Energy prices have soared since Russia invaded Ukraine and scarce supplies could push up the cost even further.

Europe is attempting to wean itself off Russian energy in an effort to reduce Moscow's ability to finance the war, but the transition may not come quickly enough.