By David Ljunggren

OTTAWA (Reuters) - The Canadian government will announce its decision on two major Enbridge Inc pipeline projects on Tuesday, two sources familiar with the matter said on Thursday.

Energy industry officials and environmental groups expect Ottawa to veto the proposed Northern Gateway line from Alberta's oil sands to the Pacific province of British Columbia and approve Enbridge's plan to replace the Canadian segments of its aging Line 3 from Alberta to Wisconsin.

The Canadian cabinet discussed the pipelines at a regular weekly meeting on Tuesday, said one source, who asked to remain anonymous because of the sensitivity of the situation.

The question of pipelines is a major political challenge for Liberal Prime Minister Justin Trudeau, who is under pressure from greens to block projects that could lead to more emissions from the oil sands.

At the same time, the energy industry wants more pipelines to ease transport bottlenecks in Alberta.

Trudeau has long opposed Northern Gateway, citing the proposed routing through a rain forest.

Line 3 currently is running at just over half capacity because of voluntary pressure restrictions.

Natural Resources Minister Jim Carr told reporters on Thursday that the Enbridge announcements would not be made on Friday "but very soon after that."

The Liberals, who came to power a year ago promising to do more to protect the environment, also must decide by Dec. 19 whether to allow Kinder Morgan Inc to more than double the capacity of its Trans Mountain line from Alberta to the Pacific.

Environmentalists and aboriginal activists are promising unprecedented protests should Ottawa approve that project and one Liberal legislator from British Columbia has publicly urged Trudeau to veto it.

Government officials, asked whether Carr might seek to delay the decision, say he is committed to meeting the Dec. 19 deadline.

(Reporting by David Ljunggren; Editing by Lisa Shumaker and Bill Trott)