Chelsea players angrily accused Norwegian referee Tom Henning Ovrebo of missing several penalty and hand-ball calls in Wednesday's 1-1 draw against Barcelona, which advanced to the final with a late goal.

London's Evening Standard newspaper reported death threats were made over the Internet against Ovrebo.

Chelsea promised Thursday to take "the strongest action" against any fans found making threats, but said it had received no evidence of any.

Security officials had to restrain a cluster of angry Chelsea players from confronting the referee as he walked off the pitch.

Striker Didier Drogba and winger Jose Bosingwa apologized Thursday for their angry reactions after the match.