Jaguar Land Rover chief executive David Smith has relinquished his position, the car manufacturer has announced.
Mr Smith's resignation comes after the company's talks with union bosses over pay and conditions failed.
But the company denied any link between the breakdown of discussions and the departure.
A spokesman for the company said: "We are disappointed the discussions ended without agreement, but his departure is not linked to the talks."
Director Ravi Kant has taken Mr Smith's place on an interim basis until a permanent successor is found, the group said.
The firm refused to comment on the details of the latest resignation, saying only that "it's a confidential matter between him and the company".
Jaguar Land Rover – now a part of India's Tata Motors group – is planning to introduce a change in its pay and pensions structure for the new starters, but six days of talks with union bosses yielded no results.
Unite leaders and the company had begun informal discussions before Christmas after the firm published its strategic review in September.
The company and Unite got together last week to talk about the review, including proposed changes to pay and pensions.
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