European shares were flat on Monday as markets struggled to hold on to the tailwind from a rebound seen last week, while London stocks led regional gains following upbeat performances by energy firms on the back of higher oil prices.

The pan-European STOXX 600 index held near 462.5 points, trading barely within a three-point range, while London's FTSE 100 index, housing Europe's top oil companies, led gains with a 0.5% climb.

The European oil & gas sector index climbed 0.9%, lifted by rising oil prices after top global exporter Saudi Arabia pledged to cut production by another 1 million barrels per day from July.

Markets struggled to sustain the optimism from gains posted on Friday after euro zone inflation eased, the U.S. averted a debt default, and receding bets that the U.S. Federal Reserve might pause interest rate hikes this month.

"Its just a consolidation from Friday's strong gains following the U.S. data, so unless there is some big catalyst in the form of macro news, we're going to be range bound," said Stephane Ekolo, global equity strategist at Tradition in London.

The STOXX 600 ended May with declines of over 3%, logging its worst monthly performance this year as much of the month went by with worries about the U.S. debt ceiling standoff and signs of a global economic slowdown.

European telecoms advanced 0.8% rebounding from its worst session in 15 months on Friday after Inc said it was in talks to offer low-priced mobile services.

Shares of Indivior Plc jumped 10% to top the STOXX 600 index after the drugmaker agreed to pay $102.5 million to settle a lawsuit for its opioid addiction treatment Suboxone.

Asos jumped 11.6% on a report that said the fashion retailer received a 1 billion pound bid from Alibaba-backed rival, Trendyol.

Swedish streaming company Viaplay Group plunged about 59% after warning of a weakening business environment as rising living costs dent demand, and said it was replacing its chief executive.

Separately, data showed euro zone business activity was shored up last month by the bloc's dominant services industry offsetting a deepening decline in the manufacturing sector, while price pressures eased.

Swiss annual inflation dipped to 2.2% as expected in May, government data showed, although the Swiss National Bank could still raise interest rates later this month.

The Copenhagen Stock Exchange was closed on Monday on account of Constitution Day. (Reporting by Shreyashi Sanyal in Bengaluru; Editing by Sherry Jacob-Phillips and Dhanya Ann Thoppil)