The tickets giveaway is likely to be repeated next week for the visit of Belgian side Genk as a supporter boycott threatens to leave the crowd well short of Stamford Bridge’s 41,800 capacity.
Sources said the 1,000-plus tickets for the Bayer Leverkusen match last month were distributed through the Chelsea Foundation, which supports the local community.
Chelsea have raised general admission prices for European games from £30 to £40 in two years.
The crowd for the Bayer Leverkusen game was around 8,000 short of capacity despite the giveaways and many expect the attendance for the Genk match to be lower still. Chelsea generally sell out for Premier League matches although there are often corporate tickets left unsold.
Chelsea chairman Bruce Buck has argued the club needs a move to a larger stadium to compete with the likes of Manchester United (capacity 76,000) and Arsenal (60,000). Buck says he is comfortable that the stadium will be full for the Genk match.