Finland's Valtteri Bottas will stay at Mercedes next season, the Formula One champions said on Wednesday ahead of the Singapore Grand Prix.

Bottas joined from Williams as triple world champion Lewis Hamilton's teammate in January after 2016 title winner Nico Rosberg retired.

"The balance of his performances and his upward trajectory made it a no-brainer for us to continue with him into 2018," said team boss Toto Wolff in a statement.

"For our team, the bonus factors are the respect and sportsmanship that have grown between our two drivers. The chemistry and dynamic between Valtteri and Lewis work and are what we need to take the fight to our competitors."