Electronic trading on the London Metal Exchange (LME) came to a halt at 09:58 BST on Tuesday, owing to a technical fault.
However, other types of trading, including open pit trading have not been affected, according to a spokesperson.
The spokesperson also said she could not give a firm time frame within which trading would resume but added that it was a "controlled halt" to proceedings with a 15 minute warning to all users on the network. No further details have been provided.
It is the latest in a string of technical faults at trading venues. Last year, Facebook's debut on the Nasdaq was hit by a technical glitch, while a software glitch at Knight Capital caused huge price swings in 140 stocks traded on the New York Stock Exchange.