TORONTO (Reuters) - Toronto's main stock index ended slightly lower yesterday, dragged down by weakness in gold miners and by investor worries that the outlook for economic recovery is uncertain.

Miner Barrick Gold sank 1.1 percent to C$46.38, while Goldcorp fell 1.7 percent to C$43.20 as a firmer greenback kept bullion prices from rising further and gold ended largely flat ahead of key US economic data due later this week.

The broader materials sector fell 0.64 percent.

"Lingering yet waning optimism regarding M&A" had kept the TSX above break-even for most of the day, but uncertainty about the economic outlook weighed on investor sentiment, said Rick Meslin, head of Canadian equities at UBS.

"What we're seeing now is people take a little bit of money off. But for the M&A optimism I'd expect the market to be a lot lower as average sentiment about whether the recovery is going to be there or not has really not become clear. I'd say sentiment is uncertain at best."

The Toronto Stock Exchange's S&P/TSX composite index finished the session down 3.44 points, or 0.03 percent, at 11,718.63. Seven of the index's 10 main groups were lower.

In individual company news, takeover target Potash Corp of Saskatchewan Inc , a top net gainer, climbed 0.7 percent to C$158.17.

The No.1 fertiliser producer was put in play by BHP Billiton's $39 billion hostile bid. Potash continues to mull its alternatives and has held discussions with China's Sinochem Group, a source close to the matter said yesterday.