Chinese companies withdrew from a Canadian pipeline project, amid delays, with China National Petroleum Corp, the parent of PetroChina, saying the Canadian government should have done more to help along a four-billion dollar pipeline project linking Canada's booming oil sands to a Pacific port.

Delays in starting the project reflected an unwillingness to allow Chinese firms into the Canadian markets, Song Yiwu, vice president of China National Petroleum said.

"The environment is not comfortable. We tried to come here and we can't," Song told the daily Globe and Mail during an investment conference in Calgary.

"We sincerely wanted to do something and open up a new market for Canadian crude, but Canada doesn't want to open up its own markets to us. So we cannot cooperate, and I really don't know how to help," he said.

PetroChina had agreed in principle with Enbridge Inc, a Calgary-based pipeline company behind the so-called Gateway project, to buy half of some 400,000 barrels of crude expected to flow each day through the pipeline.

But the project has been delayed because of lack of support by Canadian firms and native land claims along the proposed route. Enbridge pushed the completion date from 2009 to beyond 2012.

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