CEO Matthew Chamberlain told a virtual seminar that he was aware the LME might be accused of trying to shut the ring permanently, but he emphasised the need to enhance its electronic trading capability in the face of the pandemic.

The 143-year-old exchange temporarily closed what is the last open-outcry trading floor in Europe in March because of coronavirus restrictions, shifting activity to its electronic system.

"Now I understand that by raising these questions the LME might be accused of trying to further electronify the market or perhaps even close the ring right down," he said.

The world's oldest and largest market for industrial metals has imposed three conditions for reopening the ring, including the end of social distancing in Britain and the broad rollout of a coronavirus vaccine.

"We must acknowledge that it seems unlikely that any of those criteria will be met any time soon," Chamberlain said.

"If we are going to be out of the ring for a long period and pricing our market electronically, there is perhaps more that we can do to make that process even more efficient."

The LME is setting up a working group to look at improving electronic trading and examine the broader balance of electronic, ring and telephone trading, he added.

The ring closure was the first since World War II and ended the theatre of arcane hand signals and frenzied shouting by traders.

Floor dealers on the exchange, which is owned by Hong Kong Exchanges and Clearing, have resisted the shift to full digital trading during the pandemic.

(Reporting by Eric Onstad; Editing by David Goodman)

By Eric Onstad