TORONTO (Reuters) - The Toronto Stock Exchange's main index fell back from a record high yesterday, weakened by retreating oil and gas shares as investors took the opportunity to lock in profits.

The heavyweight energy sector eased 0.5 percent despite yet another record high for crude near $127 a barrel after Iran said it was studying a plan to cut oil output.

Husky Energy fell C$1.65, or 3.2 percent, to C$50.19, and Imperial Oil was down C$1.36, or 2.3 percent, at C$57.94.

"I think overall we're just really seeing a bit of a blow-off from yesterday," said Michael Sprung, president at Sprung & Co. Investment Counsel. "Our view would be that these highs aren't sustainable given the weakness in the underlying economy."

The S&P/TSX composite index closed 49.37 points, or 0.34 percent, lower at 14,616.70 yesterday with six of its 10 main sectors falling. On Monday, the index hit a record high of 14,695.75.

Shares of Rona slipped 50 Canadian cents, or 3.7 percent, to C$12.95 after the home renovation retailer reported a 90 percent drop in quarterly profit, and warned it would have a difficulty hitting its goal of low single-digit growth in earnings per share over the next few years.

Tech shares, which also helped fuel the benchmark's advance on Monday, gave up 1.3 percent amid negative sentiment south of the border over Hewlett-Packard's deal to buy Electronic Data Systems.

In Toronto, Research In Motion was off C$1.25, or 0.9 percent, to C$141.00.

On the upside, MacDonald, Dettwiler and Associates climbed C$1.21, or 3.1 percent, to C$40.45 a day after the data-processing and space-technology firm reported its first-quarter profit rose even though a robust Canadian dollar took a bite out of its revenue.

BCE Inc got a lift from talk that the parties in a dispute over financing the buyout of Clear Channel Communications had reached an agreement in principle. Several of the banks involved in the Clear Channel deal are also providing financing for the C$34.8 billion buyout of BCE.

Shares of BCE, Canada's largest telecom company, rose C$1.00, or 2.6 percent, to C$39.10.