"It's opening at 6am London," said one. Both declined to be named because they are not authorised to speak to the media. Information on what caused the outage was not available.

A spokesman for LMESelect's owner, Hong Kong Exchanges and Clearing Ltd (HKEx), said it was checking with the London Metal Exchange, operator of the platform, to find out why trading had failed to start. All media queries to LME go through HKEx during Asian trading hours.

Trading on the LME was delayed for almost four hours last July due to technical issues relating to members' ability to connect to the market.

(Reporting by Melanie Burton; Editing by Richard Pullin and Sonali Paul)