The FWA were due to host a dinner in his honour.
Pele "has undergone a series of tests which appear to point to severe exhaustion", said the FWA.
"He is on fluids while doctors monitor his recovery. Thankfully there is no suggestion of anything more serious."
Pele helped inspire Brazil to wins in the 1958, 1962 and 1970 World Cups.
He has become increasingly frail in recent years and was unable to light the Olympic flame at the opening ceremony of the 2016 Games due to ill health.
He scored 1,281 goals in 1,363 appearances during his 21-year career, including 77 goals in 91 appearances for Brazil. We wish him a quick recovery...