He told reporters that oil prices in the EU had risen by "an average of 15 per cent" in the last 12 months.
"I call on energy companies to pass on the recent cut in oil prices to consumers," said Mr Barroso.
"We will monitor prices to ensure that competition rules are being respected".
The second-biggest supplier of energy in the UK, Scottish & Southern Energy, recently announced it was pledging to cut fuel prices in the new year.
It claimed to be "optimistic" about being able to cut bills for domestic customers, but not until 2009.
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