World oil prices eased but remained above $125 on Monday after an inflow of investment funds and supply worries helped push costs to another record high, analysts said.

New York's main oil futures contract, light sweet crude for June delivery, was 56 cents lower at $125.40 a barrel.

The benchmark contract closed on Friday at $125.96 after spiking to a record $126.25 in intraday trading at the New York Mercantile Exchange.

Brent North Sea crude for June was 61 cents lower at $124.79 a barrel after briefly hitting an all-time peak of $125.90 in London on Friday before settling at $125.40.

World oil prices crashed through records every day last week and have rocketed 25 per cent since the start of the year, when they broke the $100 barrier.

Analysts cite a variety of factors for the price spikes, including rising energy demand from Asian powerhouse economies China and India, and a weak US dollar.

Unrest and militant attacks targeting oil company infrastructure in Nigeria, Africa's largest crude producer, have also pushed prices higher, analysts say.

Oil major Royal Dutch Shell said Saturday it was losing the equivalent of 30,000 barrels of crude oil per day because of recent attacks against its installations in Nigeria.

"That's quite a big, significant impact, especially in the US, because the oil is quite good quality," said Tetsu Emori, a fund manager with Astmax asset management in Tokyo.