TORONTO (Reuters) - The Toronto Stock Exchange's main index closed at its lowest level in more than seven months yesterday after early enthusiasm over the US mortgage bailout plan fizzled as worries over slowing growth weighed on resource and tech shares.

After jumping more than 2 percent early in the session, the heavyweight energy and materials sectors led the downside as worries resurfaced over how demand for commodities will fare in the face of sluggish global growth.

In the oil patch, Canadian Natural Resources slid 4 percent to C$80.00, while fertilizer producer Potash Corp of Saskatchewan was the biggest net loser, falling 5.7 percent to C$162.50.

BlackBerry-maker Research In Motion also dragged on the index, falling 3.8 percent to C$108.91, after a report that said the global smartphone market is being hurt by the slowing economy.

The S&P/TSX composite index closed down 181.59 points, or 1.42 percent, at 12,634.83 with all but two of its 10 main sectors in negative territory.

It was the lowest closing level since the end of January, when the index fell more than 600 points in one day, concluding a five-day retreat, on fears of a US recession.

The benchmark index has racked up triple digit losses in four out of the past five sessions, sending it down more than 8 percent.

The financial sector led the upside, buoyed after the US government took control of mortgage finance giants Fannie Mae and Freddie Mac on Sunday, the latest in a series of emergency steps to help the struggling US economy.

"What it does do, because they both owe so much money, is that improves credit markets generally and that's very positive for anyone owning any debt of any kind at this point," said Douglas Davis, president at Davis-Rea.

On Bay Street, all the major banks pushed higher, including National Bank of Canada, which rose 4.4 percent to C$52.51, while Canadian Imperial Bank of Commerce gained 3.4 percent to C$64.42. The sector overall gained 1.5 percent.

The energy and materials sectors lost 3.4 percent and 4.9 percent, respectively. Among the laggards, Agnico-Eagle Mines was down 7.4 percent at C$51.26, while Suncor Energy fell 6.7 percent to C$49.16.