* TSX down 88.84 points, or 0.64 percent, at 13,864.82
* Eight of the TSX's 10 main groups fall
TORONTO, Oct 26 (Reuters) - Canada's main stock index fell on Monday as resources stocks weighed and investors remained skittish about Valeant Pharmaceuticals despite its attempts to address recent allegations made against it by an influential short-seller.
The Toronto Stock Exchange's S&P/TSX composite index was down 88.84 points, or 0.64 percent, at 13,864.82 at 10:16 a.m. ET (1416 GMT).
The heavyweight energy group fell 3 percent and materials, which includes miners and other resource stocks, lost 2.7 percent on lower commodity prices and fading expectations for more global monetary easing, while banks and telecom companies were among the leading gainers.
The most influential single weight was Valeant, down 5 percent at C$145, after it fired back about "completely untrue" allegations it had used its ties with a specialty pharmacy to inflate revenue.
Gildan Activewear Inc declined 5.2 percent to C$36.14 after an analyst downgrade.
Of the index's 10 main groups, eight were in negative territory.
U.S. crude prices were down 1.3 percent at $44.04 a barrel, while Brent crude lost 0.9 percent to $47.55.
The most influential movers in the energy group were Canadian Natural Resources, which declined 1.4 percent to C$30.67, and Encana Corp, off 4.6 percent at C$10.10.
Gold miners were also among the weights even as bullion inched up off a three-day losing streak, with Barrick Gold Corp falling 2.2 percent to C$9.99, and Goldcorp Inc declining 2.3 percent to C$20.02. (Reporting by Alastair Sharp; Editing by Chizu Nomiyama)