PHOENIX -- The Mets have made no determination when they will activate left-handed reliever Billy Wagner, a high-ranking club official said prior to Wednesday's road-trip finale against the D-backs at Chase Field.

Wagner, recovering from left elbow surgery, is currently on a Minor League rehabilitation assignment and is scheduled to pitch again for Class A Port St. Lucie on Wednesday and Friday nights.

"There will be an evaluation after that to see if he continues to progress the way he's been," said Mets assistant general manager John Ricco, who is on the trip. "Obviously he's getting close because he's been out there for a while. So far, each outing has been positive, and if the next two continue along that route, then we'll have a decision to make."

Expectations were raised about Wagner's imminent return by a report published in Wednesday's New York Daily News saying the left-hander was expected to be re-activated on Sunday when the Mets are home to play the Giants.

But Ricco said that Wagner can remain on a rehab assignment until Aug. 29 and that right now there's no reason to push it. Thus far, Wagner has made five scoreless appearances, retiring 15 of the 18 batters he's faced. Wagner hasn't thrown for the Mets since he incurred the injury during the 2008 season.

Wagner has since been supplanted in the closer's role by Francisco Rodriguez, who was signed by the Mets as a free agent this past offseason. Wagner's current contract pays him $10.5 million this season. It includes an $8 million club option for next season with a $1 million buyout.

Though Wagner has a no-trade clause in the deal, he has said he'd waive it to play the remainder of the season with a contending club, if he proves to be healthy.

Ricco said that it will be a balance between performance and the medical reports as the team determines when to bring Wagner back.

"[On Sept. 1], the rosters expand," Ricco said. "You also have to take into consideration where he is in his surgery. We'll leave that up to the trainers and the doctors to determine what he should be doing at this stage. All those factors go into the mix when you're deciding. So it's possible he could continue [in rehab] after these next two [appearances] if we feel he still needs some time."

Wagner, 38, is 15 saves from reaching 400 in his career.