* TSX down 215.22 points, or 1.8 pct, at 12,014.90 * Biggest one-day drop since March 6 * Materials sector falls as gold miners and gold prices sink * U.S. services-sector data weighs on market * Manulife shares lose 2.7 pct after earnings By Jon Cook TORONTO, May 3 (Reuters) - Toronto's main stock index suffered its largest single-day drop in nearly two months on Thursday as mining and energy shares slid after weak U.S. services-sector data raised concerns about the economic recovery of Canada's largest trading partner. All 10 of the index's main sectors were lower. The heavily weighted materials group led losses, falling nearly 3 percent as gold mining shares tumbled alongside bullion prices. Barrick Gold Corp, the world's top gold producer, fell 3.3 percent to C$37.52 and Goldcorp Inc, the country's second-largest producer, lost more than 4 percent to C35.95. "That takes a big bite out of the index because the gold sector has a substantial weighting," said Fred Ketchen, director of equity trading at ScotiaMcLeod. Oil and gas companies' shares slipped between 2 percent and 3 percent as U.S. crude prices fell more than $2 a barrel. Suncor Energy slid 2.8 percent to C$31.32, and Cenovus Energy dropped 1.9 percent to C$33.95. The Toronto Stock Exchange's S&P/TSX composite index plunged 215.22 points, or 1.76 percent, to 12,014.90, its biggest one-day drop since March 6. The TSX accelerated losses after 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 revealed U.S. private-sector employment slowed last month. 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. non-farm payrolls report for April. "If those numbers come out and they're a disaster, we'll probably repeat what we see here today," Ketchen said. The U.S. data overshadowed optimism from Europe, after European Central Bank President Mario Draghi said the euro zone's economy was likely to recover this year and debt-ravaged Spain attracted good demand for 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 Craig Fehr, Canadian market strategist at Edward Jones in St. Louis. Canadian financial shares dove 1.2 percent, led by the major banks. Toronto-Dominion Bank fell 1.1 percent to C$81.71, Royal Bank of Canada was down 0.9 percent at C$55.83 and Bank of Nova Scotia slid 1.3 percent to C$53.29. The shares of Canada's top two life insurers - Manulife Financial Corp and Great-West Lifeco Inc - dropped after both reported stronger first-quarter results on Thursday, but analysts and investors weren't impressed as they looked ahead to what could be a gloomy second quarter. Manulife shed 2.7 percent to C$12.98 and Great-West Lifeco dropped 2 percent to C$24.32. Valeant Pharmaceuticals International Inc. tumbled 9.1 percent to C$50.61 after at least one analyst cast doubts about an earnings forecast that initially triggered a sharp rise in the drug company's shares. In other news, BCE Inc shares were little changed at C$40.31 after Canada's largest telephone company reported 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 inched up 0.2 percent to C$36.68. Shares of construction firm SNC Lavalin Group Inc, which is caught up in allegations of bribery and improper payments, fell 1.9 percent to C$37.31 after it vowed on Thursday to get to the bottom of any wrongdoing, but said the transactions were still a mystery. TMX Group shares gained 1.3 percent to C$47.10 after Maple Group said on Thursday it would accept a regulator's conditions on its C$3.8 billion ($3.85 billion) bid for the operator of the Toronto Stock Exchange.