MILAN, Nov 18 (Reuters) - Shares in oil companies fell on Thursday as plans by the world"s top consuming nations to release strategic reserves sent crude prices to multi-week lows, curbing enthusiasm for one of the best performing sectors across equity markets in recent months. Oil prices settled lower on Wednesday and fell more after Reuters reported that U.S. President Joe Biden"s administration has asked countries including China, India and Japan to consider releasing crude stockpiles in a coordinated effort to lower global energy prices, citing several people familiar with the matter. read more On Thursday oil prices were hovering near six-week lows. China said it was working on a release of its reserves, although it declined to comment on the U.S. request. Other Asian countries were looking into it, though they said they could not release reserves to cool oil prices. read more The oil and gas stock index (.SXEP) was the biggest sectoral loser in Europe, down 2.1%, eroding part of the stellar gains driven by a rally in oil and gas prices. Despite today"s decline, the index is up around 20% so far this year, almost keeping pace with the 22% gain for the broader market. (.STOXX) Oil majors Royal Dutch Shell (RDSa.L), TotalEnergies (TTEF.PA) and BP (BP.L) - the three largest European majors with a combined market capitalisation of more than $350 billion, were down between 1.4% and 2.3%. "After flying with fantasy forecasts of oil reaching $150 over the past few months, we are now coming back down to earth. Oil prices remain a declining asset class and this is a sector where there are fewer investments," said Michele Pedroni, fund manager at DECALIA in Geneva. "Even though oil demand remains good.. Today"s news has rung the first alarm bell to start scaling back the rally that we"ve seen over the past few months," he added. Shares in big U.S. oil groups, Exxon Mobil , Chevron , and ConocoPhillips traded down between 0.1% and 1.5% in early trading on Wall Street, following losses in the previous session when oil producers warned of impending oversupply. Their losses dragged the S&P 500 Energy index (.SPNY) to its lowest in five weeks. The request by Washington comes when rising energy prices are adding to global inflationary pressures forcing central banks to dial back pandemic-era stimulus policies. Brent crude in London was up slightly on Thursday but declined in early trading as much as 1.2% to a six-week low of $79.28 per barrel. U.S. West Texas Intermediate was down 1.6% at one point at 77.08, also the lowest since early last month. Biden also asked the Federal Trade Commission to investigate possible "illegal conduct" by oil and gas companies, citing mounting evidence of anti-consumer behaviour. read more Reporting by Danilo Masoni in Milan; Editing by Saikat Chatterjee, Emelia Sithole-Matarise and David Gregorio Our Standards: The Thomson Reuters Trust Principles