"Santi is not doing too well. He has some Achilles problems that hold him back," Wenger told British media.
"His knee is doing well but his Achilles has inflamed a little bit and we have to put him off impact (training)."
Wenger added that midfielder Jack Wilshere, who is yet to feature for the Gunners this season, would miss England's friendlies against Germany and Netherlands this month as he continues his rehabilitation from a broken calf bone.
Wenger said he expected the 24-year-old would have plenty of time to prove his fitness ahead of the June 10-July 10 European Championships in France where England have been drawn in Group B alongside Russia, Wales and Slovakia.
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"Jack is doing quite well but has still not been outside yet. Running, I think, starts again this week. Three to four weeks (until he is back)," Wenger said.
"I can understand you worry for the England team. I worry as well. I'm a supporter of England."
Third-placed Arsenal can close the gap on Premier League leaders Leicester City to three points with victory over relegation-threatened Swansea City later on Wednesday.
(Reporting by Shravanth Vijayakumar in Bengaluru. Editing by Patrick Johnston)
