Petrol prices are on the way up

Norway's Draugen oilfield, which produces 225,000 barrels a day, was closed at the weekend because of a strike among workers at the facility.

Peter Rehmer, an energy specialist at US-based technical analysts Elliott Wave International, said Opec was looking for a decisive price rise before it increased production.

"Crude will need to mount a loud, attention-getting move well above Opec's $22-$28 band before they start opening the spigots," Mr Rehmer said.

Opec last week decided against immediately implementing an automatic 500,000 barrels per day (bpd) of extra supply after a basket of Opec crude oil prices rose above the $28 a barrel threshold that the cartel agreed in March would trigger additional output.

Instead, the group will probably put off making a decision until a ministerial meeting in Vienna on 21 June, Opec delegates said.

The uncertainty has left traders confused as to what course of action will be taken.

Last week an Opec source said leading producer Saudi Arabia was considering a move that would require Opec to add as much as one million bpd of extra oil.

The influential Middle East Economic Survey says the US, the world's largest consumer, is asking Opec to increase output by more than 500,000 bpd to ease supply concerns during peak demand.

When the price of oil topped $30 in March it was its highest level since the 1991 Gulf War.

The rise was caused by a successful campaign by Opec to restrict their output.

Their action started last spring and the price of crude oil has more than doubled since then.

Although many countries' economies are now less susceptible to oil price rises than they were during the oil crisis of the 1970s, there has been growing consumer and political concern about the inflationary effects of oil's continuing high price.