MOSCOW --

Andre Villas-Boas said Thursday he will quit as Zenit St. Petersburg coach at the end of the season after he was blocked from leaving in the summer.

The Portuguese coach won the Russian Premier League with Zenit last season in his first full campaign, but his time in St. Petersburg has swiftly turned sour and he is currently serving a six-game ban for assaulting a match official.

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European media linked Villas-Boas with major clubs in various countries, including Real Madrid, but he said Zenit management refused to let him resign. Villas-Boas said he has refused a contract extension and now plans to leave.

''The club made me an offer at the end of last season. I answered with a refusal and at the end of the season I will leave the club,'' he said in comments on Zenit's website. ''But in any case we are continuing our work. We must try to get points, catch the ones who are above us and try to do well in the Champions League.''

The St. Petersburg club has had a rocky start to the season and sits third in the Russian table after seven league games, six points behind leader CSKA Moscow.

Zenit visits CSKA on Saturday in a crucial clash that will take place without Villas-Boas on the touchline after he was banned by the Russian Football Union for striking fourth official Ivan Saraev during a defeat to Krylya Sovetov Samara last month.

Villas-Boas, who previously coached Chelsea and Tottenham, has also persistently clashed with the Russian football authorities over issues such as fan racism and poor-quality pitches.

Zenit starts its Champions League group stage campaign away to Valencia on Wednesday.