(Adds details from departing opposition leader, spokesman)
July 28 (Reuters) - The leader of British Columbia's opposition party has resigned, the Liberal Party said on Friday, weeks after Christy Clark's government was ousted following a cliffhanger election in the legislature of the western Canadian province.
The right-leaning Liberal Party, unrelated to Canada's governing federal Liberals, said in a statement party executives will meet within 28 days to plan for a leadership vote.
Clark said in a statement she will leave Aug. 4. A spokesman said Clark will also resign her seat in the legislature.
Clark's government was defeated on a no-confidence vote last month after a May election in which her party was reduced to a legislative minority, paving the way for the left-leaning New Democrats to rule the province for the first time in 16 years.
The election of the NDP government, which is backed by the Greens, had raised concerns about the future of oil and gas projects such as Kinder Morgan Inc's C$7.4 billion Trans Mountain pipeline expansion, which the New Democratic Party has vowed to halt.
British Columbia Attorney General David Eby said this week the province would not unduly deny permits for Trans Mountain. (Reporting by Ethan Lou in Calgary, Alberta; Editing by James Dalgleish)