OTTAWA, Nov 17 (Reuters) - Canadian support for the construction of three major electric vehicle (EV) battery manufacturing factories will cost around 16% more than initially announced, an independent budgetary watchdog said on Friday.

Canada, home to a large mining sector for minerals critical for battery production, has pledged billions in incentives to woo companies involved in all levels of the EV supply chain as the world seeks to cut carbon emissions.

The Parliamentary Budget Officer assessed the total cost of federal and provincial government support for the three plants would be C$43.6 billion ($31.75 billion) over 10 years, 15.6% higher than the C$37.7 billion in previously announced costs.

The EV battery projects are due to be built by Volkswagen , Stellantis with LG Energy Solution and Sweden's Northvolt.

Federal Innovation Minister Francois-Philippe Champagne, who is leading the drive to attract battery plants to Canada, said the report did not capture many of the broader economic impacts on supply chains.

"These investments will generate economic benefits far greater than our government's contribution. (The report) also does not highlight that more than two thirds of the government's support is conditional and payable over a decade," he said in an emailed statement. ($1 = 1.3733 Canadian dollars) (Reporting by Ismail Shakil and David Ljunggren; Editing by Bill Berkrot)