OAKLAND, Calif. — All-Star pitcher Gio Gonzalez said Thursday the Oakland Athletics have agreed to trade him to the Washington Nationals, and the deal is nearly finished.

“It’s 99 percent done,” Gonzalez said in a phone interview. “It’s pending a physical and I’m just waiting to hear from my agent.”

ESPN.com first reported the swap Thursday.

A person with knowledge of the deal said Oakland will receive four players, including three top prospects: right-handers A.J. Cole and Brad Peacock, lefty Tom Milone and catcher Derek Norris. The person, who spoke on condition of anonymity Thursday night because the trade hadn’t been finalized, also said the Nationals would receive minor league right-hander Rob Gilliam from the A’s.

Gonzalez has been the subject of trade talk all offseason. Earlier this month, the A’s traded fellow top-tier starter Trevor Cahill to the Arizona Diamondbacks.

The 26-year-old Gonzalez, drafted 38th overall by the Chicago White Sox in 2004, confirmed the trade to The Associated Press on Thursday. He went 16-12 last season — a career high for wins after he earned 15 victories in 2010 — with a 3.12 ERA in 32 starts and was selected to his first All-Star game. The left-hander has reached 200 innings the past two seasons.

“I love Oakland and appreciate them because they gave me a chance,” Gonzalez said.

Gonzalez would give the Nationals the reliable starter they’ve been seeking for two years to go along with young arms Stephen Strasburg and Jordan Zimmermann. General manager Mike Rizzo made it a top priority last offseason to land another talented pitcher, and came through this time.

“I think we’re an outfield bat away and a starting pitcher away from really being a contender in the division,” he said late in the 2011 season.

Gonzalez was a big reason Oakland led the AL in ERA (3.56) and shutouts (17) in 2010 while holding opponents to a .245 batting average.

The Nationals went 80-81 this year to improve to third in the NL East after three straight last-place finishes in the five-team division.

A’s general manager Billy Beane is in rebuilding mode, stockpiling talent in the farm system.