Prime Minister Gordon Brown called on Sunday for international pressure on oil producers' group OPEC to bring oil prices down.

"Clearly oil prices are very high. Clearly also there needs to be some international effort with OPEC to get the oil price down," he said in an interview with Sky News.

Brown also said it was a matter for Chancellor Alistair Darling whether a two pence a litre fuel duty rise that has been postponed from April to October could be delayed further.

The Observer quoted sources in Brown's office on Sunday as hinting that the October rise may not go ahead.

Brown's comments on OPEC were among the strongest he has made on the need for action by oil producers to reduce crude prices, which have fallen back slightly after hitting a record near $120 a barrel last month.

They coincided with remarks by a senior Iranian oil official that oil prices might remain high until the end of the year and were not the result of a shortage of crude in the market.

Brown sees the high cost of petrol and energy as one of the reasons for voter dissatisfaction with his government which led to the Labour Party suffering its worst local election defeat on record last Thursday.

Brown said it was not absolutely clear why the oil price had remained stubbornly high and was rising.

Demand for oil was lower because of lower growth in Europe and the United States and lower growth in China than had been predicted at the start of the year, he said.

"So we've got to look very carefully at what is happening in OPEC and in oil prices and I think there is a strong case for putting pressure to see if we can get oil prices down," he said.

Iran, the number 2 OPEC oil producer, and other OPEC states have repeatedly blamed factors such as the weak U.S. dollar and speculation, not supply issues, for the rise.

Hojjatollah Ghanimifard, international affairs director of the National Iranian Oil Company, told reporters in Tehran on Sunday high oil prices were not caused by a supply shortage.

Consumer nations such as the United States and Britain have previously urged the Organisation of the Petroleum Exporting Countries to pump more crude to help cool prices. But OPEC has rebuffed the calls.