San Diego Chargers have been fined $20,000 by the National Football League (NFL) for failing "to immediately surrender" towels when directed to do so by an official during game against the Denver Broncos last month.
However, the NFL also said in a statement based on its investigation into the use of grip-improving 'Stickum' towels, the Chargers had not infringed any rule.
"Following a review ... the NFL has determined that the club did not violate a competitive rule by use of the towels," the league said.
"However, NFL game officials are charged with protecting the integrity and competitive fairness of the games and club staff members, like players and coaches, have a clear obligation to cooperate in this effort and comply with the direction of game officials.
"As a result of the failure of club staff to follow the directive of a game official to immediately surrender the towels when directed to do so, and to attempt to conceal the towels, the Chargers have been fined $20,000."
"Our staff member was unaware that the game official was trying to get his attention and he cooperated fully once he became aware" - Chargers statement
The league also said that, after consulting with its competition committee, it had advised all clubs that the use of towels or other products containing any type of adhesive substance was prohibited on game days until further notice.
The Chargers, who lost the game 35-24 after blowing a 24-0 halftime lead, said they would appeal the fine.
"Our staff member was unaware that the game official was trying to get his attention and he cooperated fully once he became aware," the Chargers said in a statement.
Stickum, an adhesive used to help improve grip, is widely available in powder, paste and aerosol forms.
Its use in the NFL was banned in 1981 under the Lester Hayes rule named after the Raiders player known for using it.