MONTREAL, Dec 14 (Reuters) - Canada’s biggest province, Ontario, will introduce a new rebate program worth up to C$75,000 for buyers of electric trucks, in a move that could boost domestic purchases of models by Tesla Inc and rivals like China’s BYD, a government spokesman said ahead of a Thursday announcement.

The program will offer buyers rebates of up to 60 percent of the incremental purchase cost of an electric truck, compared with an equivalent diesel vehicle, up to a cap of C$75,000 per vehicle, according to documents seen by Reuters.

Ontario’s new Green Commercial Vehicle Program, which also gives rebates on other fuel-saving devices, helps brings the province in line with other jurisdictions like Quebec, California and New York states, which offer incentives to defray the higher costs of electric trucks.

Canadian firms, including retailer Loblaw Cos Ltd, have been among the first to pre-order Semi trucks from Tesla, which has at least 285 reservations in hand, according to a Reuters tally as of Dec. 12.

Tesla has been trying to convince the trucking community that it can build an affordable electric big rig with the range and cargo capacity to compete with relatively low-cost, time-tested diesel trucks.

The rebate program comes as Ontario is working to attract electric vehicle manufacturers and parts-suppliers. The automaking province has lost ground in recent years to lower-cost jurisdictions like Mexico and the southern United States.

The rebates are being offered through a C$12 million fund, for the fiscal year ending on March 31, 2018.

The government used an existing incentive program to help attract BYD, which recently announced it will open an Ontario factory to assembly 900 electric vehicles over the next five years, Economic Development Minister Brad Duguid said by email.

BYD could not be reached for comment.

Ontario has set the target of cutting greenhouse gas pollution to 15 percent below 1990 levels by 2020, 37 percent by 2030 and 80 per cent by 2050 and the use of electric vehicles is expected to help reach that goal. ($1 = 1.2856 Canadian dollars) (Reporting by Allison Lampert; Editing by Frances Kerry)