Investing.com - Oil prices remained on the front foot on Tuesday, with Brent prices extending gains to hit another 2014 high, as looming U.S. sanctions against Iran continued to provide support.

Brent crude futures, the benchmark for oil prices outside the U.S., tacked on 23 cents, or around 0.3%, to $78.46 a barrel by 4:05AM ET (0805GMT), after climbing to $78.60 earlier in the session, its highest since November 2014.

Worries about Iran have been key to oil’s recent surge to late-2014 levels.

Prices have rallied sharply since U.S. President Donald Trump walked away from an international nuclear deal with Iran last week and reimposed “the highest level of economic sanctions” against the country.

Some analysts have said the reinstatement of sanctions could lead to tighter global oil supplies as they make it more difficult for Iran to export oil.

Iran, which is a major Middle East oil producer and member of the Organization of the Petroleum Exporting Countries (OPEC), resumed its role as a major oil exporter in January 2016 when international sanctions against Tehran were lifted in return for curbs on Iran's nuclear program.

Exiting the deal leaves the U.S. at odds with Europe and other parties to the deal, who will try to keep it in place.

It may also increase tensions in the Middle East, especially between Israel and Iran.

Meanwhile, New York-traded WTI crude futures were little changed as investors looked ahead to fresh data on U.S. commercial crude inventories to gauge the strength of demand in the world’s largest oil consumer.

Industry group the American Petroleum Institute is due to release its weekly report at 4:30PM ET (2030GMT). Official data from the Energy Information Administration will be released Wednesday, amid forecasts for an oil-stock drop of around 1.4 million barrels.

The U.S. benchmark was last at $70.98 a barrel, not far off their Nov. 2014 high of $71.89 reached last week.

Oil prices ended higher on Monday, after OPEC said a global glut has been virtually eliminated thanks in part to ongoing OPEC-led supply cuts and fast-rising global demand.