TransCanada Corp (TRP.TO), Canada's No.2 pipeline operator, said on Wednesday it would spend about $2 billion through 2021 to expand its natural gas gathering pipeline in western Canada.

The investment will be used to build new pipeline infrastructure to move natural gas from western Canada to North American markets, the company said.

The announcement comes a day after the Canadian Association of Petroleum Producers (CAPP) called for new pipelines in an annual report.

TransCanada's expansion plan will connect Montney, Duvernay and Deep Basin production to its NOVA Gas Transmission pipeline system in Alberta.

Construction is expected to begin early in 2019 and final projects to be in service by the second quarter of 2021, the company said.