SACRAMENTO (AP) — California’s attorney general is suing to block a petroleum company’s attempt to gain more control over oil, fearing it could further drive up gasoline prices.

Attorney General Xavier Becerra announced the lawsuit Thursday against Valero Energy Corporation.

“I believe that this proposed acquisition would suffocate open competition in the area and raise gas prices for hardworking Californians. That’s simply unacceptable,” Becerra said in a prepared statement. “As the state’s chief law enforcement officer, I’m committed to ensuring that we have a thriving and competitive marketplace.”

Valero wants to buy a San Francisco Bay Area petroleum terminal from Plains All American Pipeline. The terminal in Martinez imports and exports petroleum products.

Becerra says the sale would mean all three Northern California petroleum terminals would be controlled by refineries.

One of Becerra’s predecessors, Bill Lockyer, forced Valero to sell the Martinez facility in 2005 as part of an anti-trust deal after the company acquired two terminals under an earlier business deal.

Lillian Riojas, spokeswoman for the Texas-based company, did not immediately comment.