(Adds details on sectors and stocks throughout; updates prices)
TORONTO, May 28 (Reuters) - Canada's main stock index fell to a two-week low on Monday as lower oil prices pressured energy shares, while Bombardier Inc got a boost from an order to buy the company's CS300 aircraft.
* At 10:21 a.m. (1421 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 22.52 points, or 0.14 percent, to 16,053.15. It touched its lowest intraday since May 14 at 16,038.91.
* The decline for the index came as U.S. markets were closed for Memorial Day.
* The TSX's energy group retreated 1.3 percent, with major oil producer Suncor Energy Inc down 1.2 percent at C$50.16.
* U.S. crude prices were down 2.3 percent at $66.31 a barrel as Saudi Arabia and Russia said they may increase supplies while U.S. production gains show no sign of slowing.
* Bombardier said it had completed the sale of 30 CS300 aircraft to Latvia's Air Baltic Corp, valuing the firm order at about $2.9 billion based on the list price. The company's shares rose 3.9 percent to C$4.54.
* Shares of WestJet Airlines rose 1.8 percent to C$20.74. Pilots who fly for the company's budget carrier Swoop will now be unionized, a concession which resolves a key obstacle in a labor dispute with the airline, a negotiator with the Air Line Pilots Association said.
* Pan American Silver Corp shares fell 4.7 percent to C$22.28 after the company initiated steps to reduce certain activities at the Dolores Mine in Mexico.
* The overall materials group, which includes precious and base metals miners and fertilizer companies, lost 0.3 percent.
* Four of the TSX'S index's 10 main groups were lower. The index posted seven new 52-week highs and no new lows. (Reporting by Fergal Smith Editing by James Dalgleish)