Delta Air Lines has agreed to spend $315 million to expand its operations and nearly double its work force at the Greater Cincinnati International Airport.

Gov. Wallace Wilkinson said the state has agreed to limit Delta's annual sales tax liability on jet fuel to $4 million. That would require an act of the General Assembly and Wilkinson said he expects it to pass.The governor said the state also will grant tax credits worth as much as $15 million on the airline's increase in payroll.

The state is offering no incentive money up front for the expansion, which is expected to add 2,800 employees to the airline's work force in northern Kentucky.

The project will add 25 arrival and departure gates to the Delta hub already in place at the airport.

Delta Chairman Donald W. Allen said the expansion would be the largest the airline has undertaken. Cincinnati will remain Delta's fourth-largest hub, behind Atlanta, Dallas-Fort Worth and Salt Lake City.

The airline is to begin construction immediately and is scheduled to complete the project by 1994.