Tesoro Corp. has agreed to pay $260,000 in fines for nearly two dozen violations at its Contra Costa County refinery in 2011, air-quality regulators said Friday.

The 23 violations included an out-of-control flaring incident May 12, 2011, that prompted complaints from neighbors of the refinery, located in an unincorporated area near Martinez, said the Bay Area Air Quality Management District.

The agency’s executive officer, Jack Broadbent, said in a statement that oil refineries must satisfy their permit restrictions and that “missteps in their operations will not be tolerated.”

Tesoro exceeded limits on emissions of nitrogen oxides and sulfur dioxide on an undisclosed number of dates in 2011, the air-quality agency said.

The company was also fined for having leaks in tanks and failing to monitor emissions properly and report violations.

The company violated limits during the May 12 flaring event — the uncontrolled burning off of excess hydrocarbons — and failed to do a required analysis of another flaring later in 2011, the agency said.

Tesoro representatives did not return calls seeking comment.