UPDATE 2-British Columbia delays some work on Trans Mountain oil pipeline

(Adds comments from minister, professor)

CALGARY, Alberta, Aug 10 (Reuters) - British Columbia will not allow Kinder Morgan Canada Ltd to begin work on public land for its Trans Mountain pipeline expansion until it "meaningfully" consults aboriginal communities, provincial officials said on Thursday.

The $5.5 billion project through British Columbia, which secured federal government approval last year, would almost triple the capacity of the current Trans Mountain pipeline. But its prospect has become more uncertain since a left-leaning government took power in British Columbia in June.

British Columbia Environment Minister George Heyman told reporters in Vancouver it is unlikely that Kinder Morgan will be able to begin work on public land by its September construction target.

Public land represents the "vast majority" of the expansion's route, environmental group Stand.earth said on Thursday.

But Kinder Morgan's timeline for construction will not be affected, the company said in an email.

The company said it takes the British Columbia government's comments seriously and remains ready and willing to meet with provincial officials.

Shares in Kinder Morgan Canada and Houston-based parent Kinder Morgan Inc fell soon after the minister's comments and ended down 3.7 percent and 1.8 percent respectively. The benchmark Toronto share index was down 0.9 percent.

Kinder Morgan's project is critical for Canadian crude producers as they need the Trans Mountain expansion to access new markets and command better prices. Currently, their landlocked products trade at a discount to the West Texas Intermediate benchmark.

British Columbia will also seek to participate in court cases against federal approval of the project, Heyman said. The provincial government has not accepted five of Kinder Morgan's eight plans to mitigate the project's environmental impact because they do not adequately address aboriginal consultation, he added.

"Until those plans are completed, Kinder Morgan, with the exception of private land ... cannot put shovels in the ground," the minister said. But he did not specify the benchmark for consultation, a requirement under Canadian law, to be done "meaningfully."

University of British Columbia law professor Jocelyn Stacey said, given the government's stance on indigenous issues, it will likely hold Kinder Morgan to a high standard.

The Natural Resources Canada federal department reiterated its position in a statement on Thursday, saying the country's decision to approve Trans Mountain was based on facts, evidence and national interest. (Reporting by Ethan Lou; Editing by Phil Berlowitz and Lisa Shumaker)