A rogue trader has caused a spike in the price of oil and cost his firm £6 million after a series of unauthorised trades.

PVM Oil Futures said a senior broker based at the firm's London office had taken the unauthorised positions in Brent crude futures.

Heavy buying during the Asian trading day when volumes tend to be lower caused global crude prices to spike to their highest level this year.

Exchange ICE Futures Europe - where bets on the price of oil can be placed months ahead using futures contracts - is probing the flurry of trading in the early hours of Tuesday morning.

Chief operating officer David Peniket refused to comment on individual cases, but said the body would investigate unusual trading activity as a "matter of course".

PVM is the world's largest independent broker, trading more than 100 million barrels of over-the-counter and oil futures a day on average.

In a statement issued by managing director Robin Bieber, the firm said it was investigating the unauthorised trades but did not name any employee suspected of being involved.

The statement said: "PVM can confirm that it was the victim of unauthorised trading on Tuesday 30th June.

"As a result of a series of unauthorised trades, substantial volumes of futures contracts were held by PVM.

"When this was discovered, the positions were closed in an orderly fashion."

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