LONDON: Oil prices topped 80 dollars a barrel on Monday as a strike at French energy giant Total and concerns over Iran's nuclear programme rattled the market, analysts said.

New York's main futures contract, light sweet crude for delivery in March, hit an intra-day high of 80.51 dollars a barrel.

It later stood at 79.93 dollars, up 12 cents compared with Friday's close.

Brent North Sea crude for April delivery gained 13 cents to 78.32 dollars at about 1000 GMT.

"The sentiment is quite bullish at this time because of the refinery strikes in France and the concerns over Iran's nuclear issues," said Victor Shum, senior principal at Purvin and Gertz energy consultants in Singapore.

A strike by workers of energy major Total entered its sixth day on Monday.

France's government meanwhile moved to calm fears of petrol shortages during the open-ended strike at all of oil giant Total's refineries, as families hit the road for the half-term school holiday.

Some French drivers rushed to fill their tanks on Sunday after workers at Total raised the threat of shortages. AFP reporters in towns such as Rennes and Toulouse saw queues at filling stations and some pumps ran dry.

Total supplies about half of France's filling stations.

Tensions between crude-exporter Iran and the West over Tehran's alleged nuclear weapons ambitions also helped boost prices, analysts said.

The US and other world powers are drumming up support for a fourth round of UN sanctions against Iran for its refusal to comply with repeated ultimatums to suspend uranium enrichment and agree to a UN-backed nuclear fuel deal.

However, Shum warned that the rally might run out of steam as supply continues to outstrip demand.

"I think it is not sustainable at this level... there is still a lot of inventory and a lot of spare refining capacity," he said.