B.C. NDP Leader Carole James says the anti-HST petition is in response to widespread public opposition to the new tax. (CBC)

B.C. New Democrat MLAs plan to spend the August holiday weekend circulating petitions opposing the provincial government's plans to introduce a harmonized sales tax.

The 12 per cent harmonized sales tax (HST) combines the seven per cent provincial sales tax and the five per cent GST, and is scheduled to take effect next July.

But provincial NDP Leader Carole James said the New Democrats are hoping to thwart the plan and are circulating a petition that says the Liberal government has no mandate to introduce the tax.

"We're going to be circulating this wide and far all over this province," James told CBC News on Friday.

"We're going to make sure it's out with the public. We really have heard an outcry from people who have been asking for this," James said.

The way B.C.'s HST will be applied means consumers will pay an extra seven per cent tax on many items that were previously exempt from the PST, such as restaurant meals, airline tickets, funerals, haircuts, and the portion of the price of new homes over $400,000.

James said the HST is an issue that crosses party boundaries.

On Thursday, former B.C. Social Credit premier Bill Vander Zalm urged people to take to the streets in protest against the harmonized tax.