In London, reference Brent North Sea crude for June delivery rose 48 cents to $25.50 (€23.36) a barrel in late trading.
New York's benchmark light sweet crude contract for May was up 46 cents to $29.64 a barrel in early deals.
Earlier yesterday, Iranian Oil Minister Mr Bijan Namdar Zanghaneh said that OPEC needed to reduce production in the second quarter of 2003. Iran is the second-biggest producer within OPEC, behind Saudi Arabia.
"Currently there is a surplus in the oil market and, if it is not controlled in the long term, oil prices will slide," Mr Zanghaneh said at an international energy conference in Tehran.
"We need a decrease in production. . . starting the second quarter of 2003," he said.
OPEC members are due to meet next Thursday in Vienna to discuss a possible production cut, with sources in the cartel saying it could amount to as much as two million barrels per day.
"We are now a week away from the OPEC meeting, there is an expectation that they will either reduce output by cutting their quotas or by improving (quota) compliance," said Commerzbank analyst Mr David Thomas.
Prices were also being pushed upwards by traders ensuring they were not too exposed ahead of the long Easter weekend, which in London sees the markets closed until Tuesday.
"The market is higher on short covering ahead of the bank [public\] holidays, which may push oil prices slightly higher during the day," said GNI trader Mr Robert Laughlin.
"The London market tends to short-cover and square its positions because we are not opening until Tuesday whereas the [United\] States are open on Monday," he said.
