Senior officials from Iran and Libya have claimed that the global market for crude oil is oversupplied and have called on Opec to consider curbing production.

The oil producers' cartel meets in Vienna tonight and will consider how to respond to a 27 per cent slide in the price of a barrel of crude since July 11, when it hit a record of more than $147.

Hardliners, such as Shokri Ghanem, chairman of Libya's National Oil Corp, are pressing for Opec to lower production to put a floor under possible further price falls. “There is a lot of oil in the market, much more than demand,” he said yesterday. He said that this represented a supply “glut”.

His comments were echoed by Gholam Hossein Nozari, the Iranian Oil Minister, who said that Iran believed that the market was oversupplied.

Nevertheless, analysts believe the chances of Opec announcing a formal cut are slim, with several more moderate members, including Kuwait and Saudi Arabia - the world's largest oil producer and the organisation's de facto leader - expected to press for Opec's production quota of 27.25 million barrels per day to remain unchanged. Opec's 13 member states produce 40 per cent of the world's oil.

Saudi Arabia has repeatedly emphasised the need for caution, fearing the implications of another rise in prices for the fragile global economy. Ali Naimi, the Saudi Oil Minister, has talked about a floor of $80 as the trigger for action. Prices remain 14 per cent higher this year than in 2007 and a barrel of benchmark crude fetches four times what it did in 2003.

John Hall, an independent energy analyst, said that the most likely outcome would be for Opec to leave its existing production targets on hold but call for members to adhere more strictly to their individual quotas.

Actual Opec production now stands about one million barrels above its target, with Saudi Arabia accounting for the lion's share of the excess.

Much of the debate at tonight's meeting will revolve around Saudi Arabia's decision to bow to pressure from the United States this summer by independently boosting its production without Opec's agreement - a move designed to relieve upward pressure on oil prices. That increase, announced at an emergency summit of energy ministers organised by King Abdullah in Jeddah at the end of June, appears to have succeeded in its aims.

A rapid subsequent fall in prices has delighted oil consumers but left governments in many poorer producer countries, such as Venezuela and Iran, facing unwelcome budget shortfalls.

Since July 11 the price of a barrel of crude had slipped by more than $40 to as low as $105 last week, although it rallied to $108 yesterday.

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