By Jonathan Cable, Leika Kihara and Dan Burns

LONDON/TOKYO/NEW YORK (Reuters) -The global economy looks increasingly likely to be heading into a serious slowdown, just as the highest inflation in a generation prompts central banks to aggressively reverse the ultra-loose monetary policy adopted during the pandemic to support growth, data showed on Friday.

Business activity in the United States, the world's largest economy, contracted for the first time in nearly two years this month, activity in the euro zone retreated for the first time in over a year, and growth in Britain was at a 17-month low, purchasing managers' surveys said on Friday. [EUR/PMIS]

In another ominous sign for the global economy, Japan's government is expected to sharply cut its forecast for domestic growth.

Meanwhile, China's strict COVID-19 lockdowns and Russia's invasion of Ukraine have further damaged global supply chains that had not yet recovered from the pandemic.

S&P Global on Friday said its preliminary - or "flash" - U.S. Composite PMI Output Index had tumbled far more than expected to 47.5 this month from a final reading of 52.3 in June. That was the fourth straight monthly drop and was driven by weakness in the services sector, which contracted enough to offset moderate growth in manufacturing.

With a reading below 50 indicating business activity had contracted, the report will feed the vocal debate over whether the U.S. economy is back in - or near - a recession after rebounding sharply from the downturn in early 2020 at the start of the COVID-19 pandemic.

"The preliminary PMI data for July point to a worrying deterioration in the economy," S&P Global Chief Business Economist Chris Williamson said in a statement. "Excluding pandemic lockdown months, output is falling at a rate not seen since 2009 amid the global financial crisis."

In the euro zone, business activity unexpectedly contracted this month due to an accelerating downturn in manufacturing and a near-stalling of service sector growth as burgeoning costs pushed consumers to cut back on expenditure, a survey showed. [EUR/PMIS]

S&P Global's flash Composite Purchasing Managers' Index (PMI) for the euro zone, seen as a good gauge of overall economic health, fell to 49.4 in July - the lowest since February 2021 - from 52.0 in June, well below all forecasts in a Reuters poll that had predicted a more modest dip to 51.0.

Businesses across the euro zone continued to report mounting inflation pressures and an acceleration in wage growth, even as the overall growth outlook becomes increasingly murky, the European Central Bank said on Friday, based on a survey of 71 major firms.