File picture: Jonathan Ernst / Reuters.

Washington - US President Donald Trump has threatened to eliminate the subsidies that General Motors enjoys, in retaliation for the carmaker culling American jobs and plants.

"The US saved General Motors, and this is the THANKS we get! We are now looking at cutting all @GM subsidies, including ... for electric cars," Trump said on Twitter.

Trump did not explain what "subsidies" he was referring to.

GM electric vehicles are eligible for a $7500 (R104 250) tax credit under federal law, but it is not clear how the administration could restrict those credits or if Trump had other subsidies in mind.

The Republican president on Tuesday escalated his attacks on GM's plan to cut 15 000 jobs and mothball five North American factories, including four in the United States. 

GM said in a statement following Trump's comments that it was "committed to maintaining a strong manufacturing presence" in the United States after investing $22 billion (R305m) in operations here since 2009 and will add new jobs in electrification and autonomous vehicles.

The cuts will "position the company for long-term success and maintain and grow American jobs," GM said, adding that many workers at impacted plants will be able to move to other GM factories.

GM Chief Executive Mary Barra spoke to Trump over the weekend to discuss the cuts and was at the White House on Monday to meet with economic adviser Larry Kudlow.

Kudlow told reporters on Tuesday that the administration had helped GM with fuel efficiency standards and other regulations.

"We’ve done this to help you and I think his disappointment is, it seems like that they kind of turned his back on him," Kudlow said.

Why not China?

Trump also criticised GM for not closing facilities in Mexico or China.

"General Motors made a big China bet years ago when they built plants there (and in Mexico) - don’t think that bet is going to pay off. I am here to protect America’s Workers!" Trump wrote on Twitter.

White House spokesman Sarah Sanders told reporters on Tuesday that the president is looking at options.

"The president wants to see American companies build cars here in America not build them overseas and he is hopeful that GM will continue to do that here," she said.

Meanwhile, Trump and Canadian Prime Minister Justin Trudeau "discussed their disappointment in the announced closures of General Motors plants in their respective countries" during a phone call on Tuesday.

In Canada, workers returned to the assembly line at GM's Oshawa plant on Tuesday, as their union president met with Trudeau and said he was ready for "mass actions" at GM facilities.

GM said on Monday that the Oshawa plant would close in December 2019.

"We're dealing with a corporation that doesn't have any respect for Canadian and American workers, and I think we should treat them in the same vein," said Jerry Dias, national president of Unifor, which represents GM workers in Canada.

Dias said he would meet with the United Auto Workers on Wednesday and discuss the possibility of "mass actions" in GM plants across the two countries.

The wrath of the leaders of the United States and Canada dramatised the challenges GM and its Detroit rivals will face as they restructure to cope with the most dramatic technology and market shifts in decades.

Reuters