WORLD oil prices have fallen sharply after Norway's oil union called off a five day old offshore workers' strike.

June futures for benchmark Brent crude fell 50 cents to $18.80 per barrel at the close of London's International Petroleum Exchange.

Leaders of the Norwegian Federation of Oil Workers (OFS) said they decided to call off their offshore strike because of faltering support.

"The OFS leadership has decided to end the sympathy action in the North Sea," the OFS said in a statement following a union leaders' meeting in Stavanger.