The Sun says the Foxes are in a three-club fight for Denmark midfielder Wass.
All three clubs want the 28-year-old and are eyeing a cut-price £4million switch as Wass has one year left on his deal in Spain.
Claude Puel is set to finish in the top 10 this season and is plotting a push for European football, with Wass as a No8 to add quality in the middle of the pitch.
Palace boss Roy Hodgson returned to Scandinavia, where he coached earlier in his career, to sign Alexander Sorloth in January and is a huge admirer of Wass.
Swansea are looking to strengthen to avoid another relegation battle next season and could be without Ki Sung-yueng as the midfielder has not agreed a new contract.