OIL'S first-ever surge through $50-a-barrel yesterday prompted stark warnings from economists about the increasing risks posed to global economic growth by the price of crude.

Threat of ''all-out war'' in the oil-rich Niger delta was the catalyst which finally propelled US light crude futures through $50 for the first time in the 21-year history of this contract.

Shell, the biggest producer in a delta region which supplies all of Nigeria's 2.3 million barrels per day of output, and fellow oil giant ENI swiftly signalled they would not be shutting production. This was in spite of a threat from the Niger Delta People's Volunteer Force of war on the country's government from October 1, and a warning that anyone who assisted the state to make money in the region would be ''seen as a collaborator and an enemy and will be targeted''.

For weeks, the key $50-a-barrel has been threatened by one supply-side shock after another relating mainly to production from trouble-torn Iraq, politically-turbulent Russia and Venezuela, and the hurricane-hit Gulf of Mexico.

November US crude clocked up a record of $50.47-a-barrel yesterday, having gone through $50 overnight. Although it eased slightly later in the day, it was still trading around this key level last night.

North Sea Brent hit a record of $46.80 yesterday, and was last night still up 50 cents on the session at $46.43.

Weekly US stock figures are likely to dictate the path of

oil today, with recent declines in crude inventories having spooked traders.

Arab-dominated producers' cartel Opec yesterday highlighted again its inability to bring down the crude price.

Oil prices have for months now stayed much higher than experts expected. Economists yesterday highlighted serious risks to economic growth, but nevertheless remained hopeful the crude price would finally recede.

Jeremy Peat, chief economist at Royal Bank of Scotland, said of the potential impact of the oil price on growth: ''It is a significant risk - there is no doubt about that...It is one supply-side shock after another.''

Peat pointed out the Nigerian worries followed concerns about production from the Gulf of Mexico, which was hammered recently by Hurricane Ivan.

They coincided with continuing doubts over future supply from Russian giant Yukos, which is embroiled in a row with Vladimir Putin's government, and instability in southern Iraq.

He said: ''All the supply-side risks remain. These are all maintaining upward pressure on oil for longer than any of us would wish.''

Peat hoped oil prices would recede before too much longer, believing slowing global growth would help keep a lid on demand next year . He predicted that deceleration in China would play its part.

Peat said: ''We are still optimistic that US growth is going to be sustained through the second half of this year and be around trend (3.5%-plus) next year. That is on the assumption that oil prices start to ebb back later this year and get back towards $35-a-barrel next spring.'' However, he warned: ''If oil prices stay higher for longer than we anticipate, that simply marks up the downside risks in the US economy and hence for the UK and others.''

John Butler, UK economist at HSBC, predicted the high oil price could shave between 0.2 and 0.3 percentage points off UK growth next year as it acted as a ''tax on UK consumer spending'' and squeezed profit margins of companies other than oil producers.

Butler said he had not factored this into his UK growth forecast for 2005 - a relatively low 2% - ''because we don't think oil prices will stay at these types of levels''.

Julien Seetharamdoo, at Capital Economics, said high oil prices would ''shave a few percentage points'' off global growth. He thought this would hit the eurozone particularly, given its growth was lower than that in the US.

He added: ''It does seem wild - this speculation that production in Nigeria is going to stop completely because of a few armed bandits in one part of the country.''