* TSX up 79.61 points, or 0.65 percent at 12,299.81 * Valeant leads rise after source says merger talks off * Resource stocks broadly gain on commodity price gains By Alastair Sharp TORONTO, April 29 (Reuters) - Canada's main S&P/TSX stock index gained more than half a percent on Monday in a broad-based move led by Valeant Pharmaceuticals International Inc after the company pulled back from acquisition talks and helped by natural resource stocks that rebounded after Friday's tumble. With prices for gold and copper moving higher and oil steady, Canada's energy and mining stocks won back some of their value. That in turn helped the commodity-focused index outperform its U.S. peers in early trade. "What we're looking at here is a rebound in resource stocks" as the prices for their underlying commodities tick higher, said Fred Ketchen, director of equity trading at Scotia McLeod. Meanwhile, Valeant gained 4 percent to C$77.37 after its $13 billion bid for generic drug maker Actavis was put on hold, according to a person familiar with the situation. Other leading stocks included Suncor Energy Inc, up 1.4 percent to C$29.68, and Canadian Natural Resources Ltd , which gained 1.5 percent to C$30.03. By 10:10 a.m. (1410 GMT) the Toronto Stock Exchange's S&P/TSX composite index was up 79.61 points, or 0.65 percent at 12,299.81. All ten of the index's main groups were in positive territory. Ketchen said he expects more volatility on the index on Tuesday, as investors react to U.S. consumer confidence data for April and Canada's real gross domestic product reading for February.