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Oil prices fell sharply on Tuesday after US President Donald Trump said that the war in Iran would come to an end "very soon".

Crude had reached almost $120 a barrel on Monday over fears that the conflict would cause lengthy disruption to energy supplies from the Middle East, but dropped back to around $90 following Trump's comments.

Although oil prices are still significantly higher than they were before the war, European stock markets rebounded with London's FTSE 100 index rising 1.9%. Gas prices also receded. Trump said he thought "the war is very complete, pretty much", although he later warned Iran to not block the Strait of Hormuz, a shipping route crucial to global energy supplies.

"If Iran does anything that stops the flow of Oil within the Strait of Hormuz, they will be hit by the United States of America TWENTY TIMES HARDER than they have been hit thus far," he wrote on social media.

The Islamic Revolutionary Guard Corps said "in response to Trump's nonsense", that Iran's armed forces will "not allow the export of a single litre of oil from the region".

Trump told a news conference in Florida: "We took a little excursion because we felt we had to do that to get rid of some evil. Then, I think you'll see it's going to be a short-term excursion."

Brent crude fell below $84 a barrel at one point before rising to $90.21 on Tuesday.

Gas also dropped, with UK prices for month-ahead delivery falling by more than 10% to 123p a therm, well below Monday's peak of 171p.

The fall in oil prices has given traders a moment to "exhale", but energy markets remain in a state of "total tug-of-war", said Alberto Bellorin, founder and managing director oil and gas investment firm InterCapital Energy. Oil trading will "remain incredibly twitchy", he said, and prices are likely to spike if the conflict escalates and fall if it seems to be easing.

European stock markets followed the relief rally seen in the US and Asia earlier. Germany's Dax index climbed 2.6% and the French Cac 40 rose 2.1%.

Earlier in Asia, Japan's Nikkei 225 had closed up 2.9%, recovering some of Monday's losses, while South Korea's Kospi gained 5.4%. Stock markets in the region had been hit hard on investor concerns that disruptions in the Gulf could mean higher inflation and rising interest rates.

The Strait of Hormuz is crucial to the global energy market as around a fifth of the world's oil passes through the narrow waterway. But traffic through the narrow passage has all but halted since the war started more than a week ago. The boss of Saudi Arabia's Aramco, the world's biggest oil exporter, has warned of "catastrophic consequences" for markets if the route remains blocked.

Amin Nasser said global stocks of oil were at the lowest for five years and the supply disruptions meant these would be used at a faster rate. "The longer the disruption goes on... the more drastic the consequences for the global economy," he said.

On Monday, G7 nations said they were ready to take "necessary measures" to address the global supply of energy in the light of surging oil prices.

A meeting between G7 leaders and the International Energy Agency (IEA) ended without a final decision on whether the nations would release oil from stockpiles, though the matter was discussed.

Robin Mills, chief executive of Qamar Energy, an energy consultancy based in Dubai, told the BBC that there was a reluctance to use this option too early as "once the strategic reserves are gone, they're gone". However, he acknowledged it was a tough decision.

"If you believe the war is over, as Donald Trump says, then you don't need to use them. But if you believe the disruption is continuing, now is the time to put a bit of oil back and calm the market," he said.

Chancellor Rachel Reeves said on Monday that the UK had used the G7 meeting to urge "immediate de-escalation" in the Middle East and guaranteed security for vessels in the region.

"I stand ready to support a co-ordinated release of collective IEA oil reserves," she said. Before the Iran war, financial markets had been expecting a cut in UK interest rates at some point this year. But these expectations vanished after the spike in oil prices raised the prospect of higher inflation.

The yield, or interest rate, on two-year government bonds - which indicates how much it would cost to borrow money for two years - was down to 3.87% having peaked at 4.15% on Monday. Before the conflict began the yield stood at 3.5%.