Canada will apply existing foreign ownership laws to PetroChina's bid to buy Canadian oil sands assets but will not introduce further barriers to investing in the country, Prime Minister Stephen Harper said on Tuesday.

We will not be introducing further barriers to foreign investment, Harper said.

PetroChina, the world's most valuable oil company, is set to pay C$1.9 billion ($1.7 billion) for a 60 percent stake in two planned Canadian oil sands projects.

The deal would mark China's biggest investment yet in the oil sands in northern Alberta, one of the world's largest untapped oil resources.

PetroChina has signed an initial agreement to take majority control of the proposed MacKay River and Dover projects owned by Canada's closely held Athabasca Oil Sands Corp. The properties could eventually produce as much as 500,000 barrels per day.

($1=$1.10 Canadian)

(Reporting Scott Haggett; Writing by Wojtek Dabrowski; editing by Peter Galloway)