The former Leeds Rhinos player was seen gathered indoors at the Millennium Stadium on Saturday, the same day Featherstone defeated Batley Bulldogs in the second round of the Challenge Cup.
A number of participants have been photographed breaching the protocols but so far Ferres is the only person identified. An RFL investigation into the gathering is still underway.
An RFL statement confirmed: "Ferres was identified as having taken part in a behind-closed-doors gathering in the bar at Rovers Millennium Stadium on Saturday 27 March.
"Photographs received by the RFL appear to show players and others from the club socialising indoors. Such gatherings are not currently permitted – either under RFL protocols or in law.
"Ferres is the only player positively identified to date. The second-row forward will not be able to resume training with the club, or attend a Featherstone match, until Wednesday 7 April – provided the club confirms a negative lateral flow test result for him on that day. He has also been fined £250.
"An RFL investigation into the gathering is underway.
"Meanwhile, the RFL has contacted all clubs and all players to remind them of obligations and expectations around Covid protocols and behaviours. The RFL is keen to ensure that individuals, their clubs and competitions are not put at unnecessary risk as lockdown restrictions are gradually eased."