(Adds background on talks, updates stock action)
By David Shepardson and Ben Klayman
Oct 10 (Reuters) - General Motors Chief Executive Mary Barra met with senior United Auto Workers officials to discuss the No. 1 U.S. automaker's most recent proposal to end a more than three-week-old strike that has cost it over $1 billion, a union spokesman said on Thursday.
Barra met with UAW President Gary Jones and senior union negotiator Terry Dittes on Wednesday at a time when GM had not yet received a formal response to a new offer made on Monday morning, sources briefed on the matter said.
GM declined to comment on the meeting, but said progress was being made in the talks.
"There was no secret meeting. There was a meeting (between Barra and Jones and Dittes) and we continue to meet at all levels," UAW spokesman Brian Rothenberg said.
The strike began on Sept. 16, with the UAW's 48,000 members seeking higher pay, greater job security, a bigger share of the automaker's profit and protection of healthcare benefits.
Apart from costing GM more than $1 billion, the work stoppage has forced it to idle operations along with nearly 10,000 workers in Canada and Mexico.
U.S. President Donald Trump and many lawmakers have also urged GM to build more vehicles in the United States, shifting work from Mexico. The union's membership is largely in the Midwest, in states that could be critical to both sides in the 2020 presidential election.
On Sunday, the UAW said the talks took a "turn for the worse" and on Tuesday urged GM to boost U.S. vehicle production. GM's production of trucks and sport-utility vehicles in Mexico has drawn anger among union workers.
GM said in November 2018 it would close four U.S. factories, including two assembly plants, and cut 15,000 jobs in North America.
GM said last month just before the strike began that it had offered to make $7 billion in new U.S. investments in eight facilities in four states, but did not specify timing, location or products with the exception of a planned electric truck.
Reuters previously reported GM told the UAW it could build a new battery plant near the now-shuttered Lordstown, Ohio, factory, and build the electric truck at its Detroit Hamtramck plant.
UAW workers are concerned that as GM shifts to more electric vehicles it will require fewer workers, and battery production may result in workers getting paid less than at existing transmission plants.
The Wednesday meeting between Barra and the UAW lasted more than 30 minutes and took place at GM's headquarters, where negotiations are ongoing. Barra's goal was to get the talks moving again, the sources said. UAW officials have previously urged Barra to involve herself in the negotiations.
Anderson Economic Group said Thursday GM has lost $1.13 billion in profits since the strike began, while employees have lost more than $624 million in wages.
GM shares were up about 1.5% in Thursday afternoon trading.
The meeting was reported earlier by the New York Post.
(Reporting by David Shepardson in Washington and Ben Klayman in Detroit Editing by Nick Zieminski)