Nearly two months before notifying federal regulators and the public that it was recalling cars with a dangerously defective ignition switch, General Motors placed an urgent order for 500,000 replacement switches, emails to its supplier Delphi Automotive show.

The emails were sent on Dec. 18, 2013, a day after a committee discussed the switch issue but adjourned without ordering a recall. Despite the official inaction, a GM representative sent an email to Delphi the next day requesting the half-million replacement parts for “an urgent field action for our customers.”

Aside from adding to the evidence that GM was maintaining a public silence about the switch while focusing with increasing intensity on it internally, the disclosure of the emails highlights a vulnerability for the company as it faces a mountain of litigation over the faulty switch.

Delphi was in close contact with GM for years as engineers developed, and then tried to correct, the problematic switch, and the company could become a factor in the lawsuits if it cooperates fully with lawyers representing accident victims and their families.

“Delphi is refusing to participate in the cover-up,” said Robert Hilliard, one of three lead plaintiffs attorneys in federal multidistrict litigation against GM. “They are fully and honestly disclosing what we have a right under the rules to know.”

The emails showing the December order were produced by Delphi during discovery in the sweeping federal litigation. Hilliard obtained permission from Delphi to declassify them. Their existence was first reported by The Wall Street Journal. Hilliard said he planned to depose current and former Delphi employees.

Since the 500,000-switch order was quietly placed, GM has recalled 2.6 million cars for the defect, beginning in early February, and has acknowledged that some engineers and others in the company knew of the flaw for more than a decade.

GM reacted to the disclosure of the emails with a statement that noted the steps it has taken after the ignition-switch recall to ensure quicker and closer attention to safety issues.

Mary Barra, who took over as GM’s chief executive in January, has said she did not learn of the ignition-switch defect until a committee decided on Jan. 31 to recall the cars. But the size and expense of the mid-December order, $2.6 million, raises questions about who approved it and why the company continued to delay an official recall of the cars.