Dec 2 (Reuters) - Canada’s main stock index traded flat on Wednesday, as losses in heavyweight mining and utilities stocks outweighed optimism over a quick economic recovery after Britain approved a COVID-19 vaccine. * At 10:31 a.m. ET (1531 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was up 9.4 points, or 0.05%, at 17,306.33. * U.S. crude prices were up 0.9% a barrel, while Brent crude added 0.8% as investors awaited a pact from producers on output, which many traders expect will continue to be reined in. * Britain on Wednesday became the first country in the world to approve the Pfizer-BioNTech COVID-19 vaccine for use, saying it would start rolling it out early next week. * Canadian labor productivity fell by a record 10.3% in the third quarter as hours worked rebounded faster than business output. * The materials sector, which includes precious and base metals miners and fertilizer companies, lost 0.1% as base metal prices retreated from recent highs. * The energy sector climbed 1%, while the utilities sector sank 0.9%. * The financials sector gained 0.1%. Royal Bank of Canada and National Bank of Canada beat expectations for fourth-quarter profit on lower-than-expected provisions to cover potential loan losses. * On the TSX, 92 issues were higher, while 124 issues declined for a 1.35-to-1 ratio to the downside, with 62.80 million shares traded. * The largest percentage gainers on the TSX were Blackberry Ltd, which jumped 13.8%, adding to more than 19% rally on Tuesday and Lightspeed Pos Inc, which rose 8.9% after brokerages raised their price targets on the stock. * Methanex Corp fell 3.9%, the most on the TSX. The second biggest decliner was Firstservice Corp, down 3.1%. * The most heavily traded shares by volume were Blackberry Ltd; Zenabis Global Inc, which was flat and Aurora Cannabis, up 1.8%. * The TSX posted three new 52-week highs and no new lows. * Across all Canadian issues there were 13 new 52-week highs and four new lows, with total volume of 110.51 million shares. (Reporting by Ambar Warrick and Devik Jain in Bengaluru; Editing by Shailesh Kuber)