South Wales Police says a body has been found in the River Ely, near Penarth Road in Cardiff.
Formal identification has not yet taken place.
The family of 34-year-old Ben Thompson from Haverfordwest, who has been missing for more than a month after watching Wales play in the Six Nations, has been informed and are being kept updated by family liaison officers.
More top news
Cold with frost and fog inland,a little milder but breezy around the coasts!
UKIP's candidate in the Rhondda quits party claiming it's turned its back on the people it claims to represent
It follows an online campaign to give Iestyn Baldwin, from Bridgend "the best birthday ever".