The global gold price setting benchmark or "fix" is open to manipulation, said the head of the London Metal Exchange (LME), which is competing to offer an alternative to the silver fix when the system is disbanded in August.

The gold and silver fixes, along with other commodity benchmarks, have come under increasing scrutiny by regulators in Europe and the United States since a London Interbank Offered Rate (Libor) manipulation case last year.

"When people sit around a table and lift a flag in the gold market and say this is where the price is, obviously it is open to manipulation if it's done in this opaque way," LME Chief Executive Garry Jones told a conference in London on Tuesday, giving no further details.