* Q1 net C$0.67/shr vs C$0.36
* Qtrly dividend increased to C$0.30/ shr from C$0.20
* Production rises, costs fall (Adds details)
CALGARY, Alberta, April 28 (Reuters) - Profit at Canadian Oil Sands Ltd COS.TO, which has the biggest stake in the Syncrude Canada Ltd oil sands consortium, rose 84 percent in the first quarter due to higher production and prices, the company said on Thursday.
It also said it would raise its quarterly dividend by half, to 30 Canadian cents a share for the second quarter from 20 Canadian cents.
Canadian Oil Sands, which converted out of the trust format at the beginning of the year in step with federal tax changes, earned C$324 million ($340 million), or 67 Canadian cents a share, in the quarter, up from a year-earlier C$176 million, or 36 Canadian cents.
The company had been expected to earn 62 Canadian cents a share, according to the average estimate of analysts polled by Thomson Reuters I/B/E/S.
The company's cash flow, a key indicator of its ability to pay for new projects, more than doubled to C$478 million, or 99 Canadian cents a share, from C$225 million, or 46 Canadian cents, in the first quarter of 2010.
Canadian Oil Sands has a 37 percent stake in Syncrude, one the largest miners and processors in the tar sands of northern Alberta.
It said its results were aided by a 13 percent rise, to C$94.60 a barrel, in the price fetched by Syncrude's synthetic crude oil, along with a 22 percent increase in production.
During the first quarter, the company's share of Syncrude's production averaged 120,894 barrels per day, up from 99,286 bpd the same period in 2010.
Operating costs were C$35.53 a barrel, down 6.2 percent. However, the company raised its forecast for average operating costs in 2011 to C$37.51 per barrel.
$1=$0.95 Canadian Reporting by Scott Haggett; editing by Peter Galloway