There were smiles and handshakes between union leaders and the General Motors chief executive, Mary T. Barra, when contract talks started in July. On Wednesday, with talks stalled and G.M. plants idled for more than three weeks by a nationwide strike, Ms. Barra sat down with the union again.

At G.M.’s initiative, Ms. Barra met for nearly an hour with the United Auto Workers president, Doug Jones, and the union’s lead negotiator, Terry Dittes, according to two people close to the contract negotiations.

They said the meeting was held at the Renaissance Center, the Detroit office complex where the negotiations are taking place, and was the first time Ms. Barra had met face to face with union officials since the ceremonial opening of the contract talks. G.M.’s headquarters are in the same complex.

The meeting was first reported by The New York Post.

The two people close to the negotiations would not characterize the substance or tone of the meeting with Ms. Barra or say whether it had helped bridge differences. But they said that some negotiators worked past midnight that night, and that the two sides were talking into the evening on Thursday.