The price of oil has tipped beyond $67 per barrel amid concerns Iran will limit oil supplies, due to its ongoing nuclear dispute with the US.
Concerns over supplies are pushing oil prices higher
Light crude for May rose as high as $67.90 a barrel in the US on Monday, before settling 11 cents up at $66.74.
The high price comes as Iran has tested what it claims is the world's fastest underwater missile.
Last week the UN told Iran it had 30 days to stop enriching uranium and comply with international rules.
London's Brent crude oil rose 93 cents to settle at $66.84 a barrel.
"A lot of uncertainty remains in how the Iranian situation will work itself out" said Victor Shum, energy analyst with Purvin & Gertz in Singapore.
The price of crude contracts rose last week as analysts had concerns about lower US inventories over the summer, while US plants are shut down for standard maintenance and prolonged unplanned outages.
US petrol stocks have fallen by almost 10 million barrels in the past four weeks, and analysts predict this trend will continue.
Any disruption to supplies, especially before demand peaks in the summer driving season is seen as a cause for concern.
Another factor that has been pushing up oil prices has been attacks on pipelines in Nigeria.
Almost a quarter of Nigeria's output - amounting to 550,000 barrels of oil per day - has been closed for six weeks following attacks on pipelines by militants in mid-February.