Oil and gas prices rose on Thursday and Asian stock markets retreated as the two-week ceasefire in Iran looked increasingly shaky, with Israel continuing attacks on Lebanon and the US and Iran threatening a return to military action.

A day after the US and Iran announced an 11th-hour ceasefire, including an agreement to reopen the strait of Hormuz, many questions remain and there were signs that the truce was already being broken, causing jitters in the markets.

Brent crude, the global benchmark, rose more than 2% on Thursday but remained below $100 a barrel, at $96.77, while New York light crude climbed almost 3% to $97.23 a barrel. On Wednesday, Brent tumbled 13.29%, falling to a four-week low of $94.75 a barrel.

Gas prices also crept up again, with the month-ahead UK gas contract up 1% at 115.35p a therm, having dropped 15% on Wednesday after the ceasefire was announced.

European natural gas futures rose towards €46 a megawatt hour on Thursday, rebounding from a five-week low. They had plummeted almost 15% to €45.30 a megawatt hour on Wednesday.

The UAE and Kuwait said their air defences had intercepted drones from Iran, while Tehran’s parliament speaker, Mohammad-Bagher Ghalibaf, said Israel and the US had violated several points of the agreement.

The Revolutionary Guards warned of a “regret-inducing response” if Israel did not stop its strikes against Lebanon. The Fars news agency reported that the passage of oil tankers through the strait was halted because of Israel’s barrage of strikes on Lebanon on Wednesday, the worst since the war started, killing at least 254 people and wounding at least 837.

Donald Trump posted on his Truth Social platform that US forces would “remain in place in, and around, Iran, until such time as the REAL AGREEMENT reached is fully complied with”. He threatened that if it were not complied with, the military action would be “stronger than anyone has ever seen before”.

In Asian stock markets, Japan’s Nikkei fell 0.7% after Wednesday’s bounce of 5.4%, while South Korea’s Kospi lost 1.7% after rising 7.5% the day before, and Hong Kong’s Hang Seng edged 0.4% lower.

European stocks also opened lower, as the optimism from Wednesday’s rally faded. The UK’s FTSE 100 index slipped 0.1%, while the German Dax fell 0.6%, France’s Cac dropped 0.3% and Italy’s FTSE MiB is down 0.2%. The pan-European Stoxx 600 index edged 0.1% lower after Wednesday’s near 4% rise, its best since 2022.

US stock futures are pointing to a lower open on Wall Street later.

Jim Reid, a strategist at Deutsche Bank, said: “Nevertheless, compared to 24 hours ago, the market stress has eased considerably, as the ceasefire news and hopes for a de-escalation pathway have created a lot more optimism.” He said fears had eased considerably about a stagflationary shock.

There are still signs of progress, with the White House press secretary, Karoline Leavitt, saying that the vice-president, JD Vance, would lead a delegation to Islamabad, with a first round of talks scheduled for Saturday morning.

Mohit Kumar, the chief European economist at Jefferies, said: “Despite the fragile nature of the ceasefire, we believe that the truce will hold. Not because we believe that a solution has been found but because of the MAD (mutually assured destruction) principle.

“We have reached a stage where both parties would want a ceasefire as carrying on the war assures a negative fallout for both parties. Trump wants a deal as he does not have support from his Maga base to continue to war. US and Israel have realised that without a solution to cheap drone interceptors and someway to bypass the strait of Hormuz, it’s a war that cannot be won.”