UK economy surged ahead of Iran war, but energy shock to test resilience

* UK GDP rises 0.5% in February, much more than forecast

* Data suggest UK economy was in slightly better shape than feared

* But Iran war spoils outlook, with Britain vulnerable to fallout

* UK GDP set for another strong Q1, stoking data adjustment concerns

* ONS says it is confident in quality of its figures

By Andy Bruce

LONDON, April 16 (Reuters) - Britain's economy put on a burst of growth in February, suggesting it was in slightly better shape before the start of the Iran war than many economists had feared, official figures showed on Thursday. Gross domestic product expanded 0.5% month-on-month in February, the biggest increase since January 2024, the Office for National Statistics said. Economists polled by Reuters had forecast a much more modest reading of 0.2%. While the figures are likely to cheer finance minister Rachel Reeves, economists said Britain remained vulnerable to the fallout from the Middle East conflict, being highly dependent on imported energy and prone to higher inflation than peers.

"Unfortunately, the latest energy price shock has likely pulled the rug on this momentum, with another year of above-target inflation and a softening labour market likely to come," said Fergus Jiminez-England, associate economist from the National Institute for Economic and Social Research. Britain suffered the sharpest cut to economic growth forecasts for large rich economies by the International Monetary Fund due largely to the Iran war, in forecasts published on Tuesday.

SERVICES SECTOR SPURRED FEBRUARY ECONOMIC GROWTH

"Growth increased further in the three months to February led by broad-based increases across services," ONS chief economist Grant Fitzner said. "Meanwhile car production recovered from the effects of the autumn cyber incident."

Economic growth for the three months to February was 0.5%, the ONS said, putting Britain's economy on track for a conspicuously strong first quarter, for a third year running.

That pattern has led to suspicions among some economists that the ONS' process of seasonal adjustment has gone awry following unusually large swings in output during the COVID-19 pandemic - something the ONS rejects.

"We're confident in our figures and seasonal adjustment processes," an ONS spokesperson said on Thursday, adding that statisticians had looked thoroughly at the issue.

James Smith, economist at ING, said he still doubted whether the ONS had fully accounted for the influence of the last period of high inflation in its seasonal adjustment process, and the timing of price increases.

"We wrote in our reaction to the January data that February or March could see a strong bounce back for exactly this reason," Smith said.

"Suffice to say, all of this is old news anyway, given the crisis we find ourselves in today." (Reporting by Andy Bruce; Editing by Suban Abdulla, Paul Sandle and Hugh Lawson)