* TSX down 135.73 points, or 1.1 percent, to 12,094.39 * Materials fall on gold miners * U.S. services sector data weighs on market * Manulife shares fall 2.5 percent after earnings By Jon Cook TORONTO, May 3 (Reuters) - Canadian stocks extended losses on Thursday, falling more than 1 percent as mining and energy firms slid on weak U.S. data that heightened concerns about the recovery of Canada's largest trading partner. The U.S. data offset a more upbeat euro zone outlook from the European Central Bank. Thursday's report by the Institute for Supply Management revealed the pace of growth in the vast U.S. services sector slowed more than expected in April. It followed Wednesday's ADP data that showed slower U.S. private sector employment last month. "The economic data remains relatively lumpy," said Craig Fehr, Canadian market strategist at Edward Jones in St. Louis, Missouri. "The market's going to react in kind to the fact that data is not pointing all to the upside or coming in well ahead of expectations in the near term." The ISM number countered earlier data on Thursday that showed U.S. jobless claims fell more than expected last week, giving mixed signals ahead of Friday's key U.S. nonfarm payrolls report for April. Nine of 10 main sectors in the Toronto Stock Exchange's S&P composite index were lower. The heavily weighted materials group led losses, falling nearly 2.6 percent as gold mining shares were hurt by weaker bullion prices. Barrick Gold Corp, the world's top gold producer, fell 3.7 percent to C$37.37 and the country's second-largest producer, Goldcorp Inc, fell 4 percent to C$36.06. Oil and gas firms slipped 1.5 percent, led by Suncor Energy , down 2 percent to C$31.58, and Cenovus Energy, which dropped 1.8 percent to C$34. At noon (1600 GMT), the TSX index was down 135.73 points, or 1.1 percent, to 12,094.39, on track for its biggest one-day drop in more than a week. The U.S. data overshadowed optimism from Europe, after ECB President Mario Draghi said the euro zone economy was likely to recover this year and debt-ravaged Spain saw good demand from some key bond auctions on Thursday. "Today the market is being largely defined by what comments we get out of the ECB in terms of their potential to foster more growth or become more accommodative with policies," said Fehr. Canadian financial shares edged down 0.3 percent, led by top insurer Manulife Financial, which fell 2.5 percent to C$13.01 after it reported a first-quarter profit on Thursday, but said it could take a charge of C$700-C$800 million in the second quarter. In other news, BCE Inc shares fell 0.8 percent to C$39.99, despite reporting on Thursday that its first-quarter profit grew 14 percent. On Wednesday, Canada's Competition Bureau gave Bell and Rogers Communication Inc the go-ahead to buy a majority stake in Maple Leaf Sports and Entertainment for C$1.32 billion ($1.34 billion). Rogers' shares were flat at C$36.63. TMX Group shares rose 1.1 percent to C$47 after the Competition Bureau signaled on Thursday that its concerns over Maple Group's C$3.8 billion takeover bid for the Toronto Stock Exchange operator may be allayed by the Ontario Securities Commission's draft rules for allowing the deal to go ahead.