UPDATE 1-Pressure in defunct Nord Stream 2 pipeline plunges overnight, cause unknown

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BERLIN, Sept 26 (Reuters) -

Authorities in Germany are trying to establish what caused a sudden drop in pressure in the defunct Nord Stream 2 gas pipeline, with a spokesperson for the pipeline's operator telling Reuters on Monday it could have been caused by a leak.

Pressure in the undersea pipeline dropped from 300 to 7 bars overnight.

The Russian-owned pipeline, which was intended to double the volume of gas flowing from St. Petersburg under the Baltic Sea to Germany, had just been completed and was filled with 300 million cubic metres of gas when German Chancellor Olaf Scholz cancelled it shortly before Russia invaded Ukraine.

European countries have resisted Russian calls to allow the Nord Stream 2 pipeline to operate, amid an escalating energy standoff since the outbreak of the war.

"We are currently in contact with the authorities concerned in order to clarify the situation. We still have no clarity about the causes and the exact facts," said a statement from the German economy ministry.

The Swiss-based operator, which has legally been wound up, said it had informed all relevant authorities and that the leak, if that were the cause, could not have been at the landing point in Lubmin, northern Germany.

"If it were in Lubmin, you'd have heard it," the spokesperson said.

Gazprom referred questions about the incident to the Nord Stream 2 operator. (Reporting by Thomas Escritt and Christian Kraemer; writing by Matthias Williams; editing by Paul Carrel)