Russian energy giant Gazprom on Friday said its key Nord Stream pipeline that supplies gas to Europe will remain shut due to a technical issue and cannot be operated until it is fixed. "Gas transmission via the Nord Stream gas pipeline has been fully shut down until the operational defects in the equipment are eliminated," Gazprom said in a statement shared on Twitter. It noted that a leak of oil was detected during maintenance works at the Portovaya compressor station. Gazprom had halted gas deliveries to Europe via the Nord Stream pipeline for maintenance works for three days on Aug. 31, and was due to reopen on Saturday. Citing Siemens, the state-run energy company said the oil leaks in the engines cannot be fully eliminated unless repairs take place at a specialized repair facility. In its press release on July 27, Gazprom said it would reduce the daily natural gas delivery capacity to Europe via the Nord Stream pipeline to 20%.