Inflation in the eurozone jumped more than expected to reach its highest level in three years in September, as the war in the Middle East fueled a surge in energy costs, official data showed Friday.

The consumer price index in the 21 nations sharing the euro currency jumped to 3.8% last month, driven primarily by fuel, natural gas, and to a lesser extent, food costs, according to data from Eurostat, the ​EU's statistics agency.

The figure is up from 3.2% in August and is higher than the 3.7% forecast by economists for Bloomberg and 3.6% estimated in a Reuters poll.

Inflation is likely to increase further in the coming months on soaring energy costs, keeping pressure on the ECB to hike rates again and governments to help struggling consumers.

A closely watched 'core' figure, which excludes volatile food ​and fuel prices and signals underlying trends, accelerated to 2.5% from 2.4%, on a pick-up in services prices, the data showed.

Rising fuel costs are putting pressure on European governments to support households and businesses, ⁠and in some countries such as France have already triggered street protests, potentially stretching already precarious public finances.

While subsidies have been minor so far, ​totalling around 0.1% of the bloc's GDP, they are less targeted and temporary than hoped, suggesting more lasting budget pain.

For the ECB, the figures are ​likely to be seen as a mixed bag.

The rise in headline inflation further above its 2% target is worrisome and will bolster calls for rate hikes on top of the two moves this summer.

As the U.S. war against Iran drags on, the conflict has caused major disruptions to fuel supplies from the Middle East, including from the Strait of Hormuz, a key energy trade route.

Energy price increases surged to 18.8% in September, up from 14.3% a month earlier, Eurostat said.

Meanwhile, food and drinks inflation increased to 1.4% from 1.1% in August.

Eurozone inflation was last above 3.8% in September 2023, when it stood at 4.3%.

Will ECB maintain its 'measured' policy response?

The muted increase in core figures indicates that high energy costs have yet to generate the sort ​of second-round impacts that could set off a hard-to-break inflation spiral.

These would suggest the ECB can stick to its 'measured' policy response, an undefined concept ​taken by markets to mean spaced-out rate hikes, perhaps to coincide with quarterly economic projections.

"September's (inflation) data don't alter our view that the ECB is most likely to ‌wait ⁠until December to raise interest rates again," Jack Allen-Reynolds at Capital Economics said. "That said, if energy prices rose further in the next few weeks, an October hike would not be a big surprise."

Investors see up to three more hikes in the ECB's 2.5% deposit rate in the coming year, but the odds of a move this month are seen as negligible and the next increase is not fully priced in until January.

These expectations change ​rapidly, however, and even policymakers acknowledge ​that their own projections are far too ⁠uncertain.

Policy hawks argue that energy costs have been too high for too long, so they are bound to start setting off second-round effects, and the recent surge in natural gas costs will feed into core prices more ​quickly than in the past, lifting everything from electricity and heating costs to business expenses.

But others say the ​labor market is ⁠relatively soft, so workers can hardly demand big pay increases, and the recent sharp increase in longer-term borrowing costs is also bound to curtail price growth.

Ultimately, the clincher for the next rate decision may be considerations for financial stability rather than inflation.

Borrowing costs have soared, mostly as the blowout in U.S. yields to a ⁠24-year high ​affects every borrower. But investors are also demanding a greater premium to hold riskier ​assets and the spread on French debt over similar German bonds has risen to multi-decade highs, raising debt sustainability questions.

Economists say the ECB may be keen to stay on the sidelines ​for now and not add to the turbulence, especially since inflation trends do not require urgent or forceful action.