Arsenal manager Arsene Wenger was handed a two-match European ban for failing to abide by the conditions of a previous suspension and will miss Wednesday's Champions League qualifier at Udinese, UEFA said on Monday.
UEFA's disciplinary board also fined the English Premier League club 10,000 euros (12,608 pounds) "for improper conduct by its officials" during last week's play-off round first leg, which Arsenal won 1-0.
The Frenchman was banned from that game for his behaviour in last season's round of 16 tie at Barcelona.
However, television pictures showed him sitting in the stands and talking on a mobile phone during the first half, apparently passing instructions to the team bench.
"Wenger was serving a one-match suspension in the Udinese home match," UEFA said.
"The UEFA disciplinary regulations stipulate that a manager may not communicate with his team during a fixture for which he is suspended and may follow the game from the stands only."
Wenger's suspension is a further blow for Arsenal, who have taken part in the Champions League for the past 13 seasons and could see that run ended on Wednesday.
The London club have been hit by injuries and the departure of captain Cesc Fabregas, sold to Barcelona.
They have taken only one point from their two first Premier League matches, although that would pale into insignificance if they miss out on qualification for the Champions League.
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