Ford Motor Co has reached a tentative deal with the United Auto Workers union on changes to retiree health care, becoming the first Detroit automaker to secure union concessions on the key issue.

Ford's shares surged 17 percent following the news of the deal. Shares of larger rival General Motors Corp were up 6 percent.

The union did not reveal the changes made to the Voluntary Employees Beneficiary Association, or VEBA, but said the proposed modifications will be presented to the union's local leadership at a council meeting early this week.

The modifications will protect jobs for UAW members by ensuring the long-term viability of the company, UAW President Ron Gettelfinger said in a statement.

Any changes to the contract would have to be ratified by UAW members at Ford, while the proposed changes to the VEBA will require court approval, the union said.

The union had already reached a tentative agreement with the automaker on other modifications to the labor contract on February 15.

As part of a $17.4 billion U.S. government bailout, rivals General Motors Corp and Chrysler LLC are required to make half of planned contributions to VEBA trusts for retiree health care in company stock.

Ford, which has not accepted any government loans, has said it expected the union to provide parity any concessions granted to its U.S.-based rivals.

(Reporting by Poornima Gupta, editing by Maureen Bavdek)