VANCOUVER -- A proposed class-action lawsuit says British Columbia's 15-per-cent tax on foreign nationals who buy homes in the Vancouver area is unfairly prejudiced against people from Asia, who have historically faced discrimination in the province.

Amended documents filed in B.C. Supreme Court last week argue the so-called foreign-buyers' tax is unconstitutional because it violates equality rights by making an "arbitrary" distinction between those who are citizens and permanent residents of Canada and those who are not.

The lawsuit, which was originally filed in September, says the tax unfairly assumes foreign nationals are wealthier than Canadians, and argues it violates dozens of international treaties guaranteeing equal treatment to non-Canadian citizens and permanent residents.

The B.C. government introduced the foreign-buyers' tax last summer in an effort to quell Metro Vancouver's overheated real-estate market, which saw July prices for detached homes soar 38 per cent over a single year.

The representative plaintiff in the proposed class action is Jing Li, a Chinese national who learned she would have to pay an additional $83,000 on a $587,000 home in Langley that she agreed to purchase days before the government announced the new tax.

Earlier this year, Premier Christy Clark tweaked the rules around the law exempting anyone living in B.C. on a work permit and who pays taxes in the province.