Chelsea striker Didier Drogba has signed a new four-year contract that will keep him with the English champions until 2010, the club said on Friday.

Drogba, who signed from Olympique Marseille in 2004 for a reported 24 million pounds ($45.78 million), had less than two years left on his old deal.

"I am not playing well just because I wanted to sign a new contract, I am playing well because I feel good and I am happy to train with my friends," Drogba told the club's web site.

"I want to say thank you to (manager) Jose (Mourinho) for believing in me since the beginning and now we will be together for a long time. The best period of my career I think.

"I am happy because when I came here it wasn't easy for me to say I would be signing a new contract with Chelsea, because everybody knows the first year was difficult.

"The second one was okay but I knew I could do better," said the 28-year-old Ivory Coast international.

Drogba has scored five times in the Premier League this season and is joint top scorer in the Champions League with five goals, including the injury-time equaliser in a 2-2 draw at Barcelona on Tuesday.