European gas and power prices have surged as panic over Russian supplies gripped markets and politicians warned citizens to brace for a tough winter ahead.

Benchmark gas settled at a record high, while German power surged to above €700 ($696) a megawatt-hour for the first time. Russia said it will stop its key Nord Stream gas pipeline for three days of repairs on Aug. 31, again raising concerns it won’t return after the work. Europe has been on tenterhooks about shipments through the link for weeks, with flows resuming only at very low levels after it was shut for works last month.

"The catastrophe is already there,” Thierry Bros, a professor in international energy at Sciences Po in Paris, said. "I think the major question is when EU leaders are going to wake up.”