Valtteri Bottas is still tied to Williams for another year. File picture: Aly Song / Reuters.

London - A new round of talks is expected soon as Mercedes is reportedly after Williams driver Valtteri Bottas to replace retired Formula One world champion Nico Rosberg.

British media reported on the weekend that Williams has rejected an offer from Mercedes to get the Finn out of his contract, which runs one more season.

Mercedes seems to prefer Bottas over other candidates such as German Pascal Wehrlein because he has more experience with 77 grands prix and nine podium finishes in four years.

Mercedes motorsport chief Toto Wolff is said to have offered a big engine discount for Williams, which is powered by Mercedes.

In addition, Wolff is part of Bottas' management team and is a former shareholder at Williams.

But the 27-year-old Bottas is to be Williams' new number one driver in 2017 after the retirement of Felipe Massa, with Canadian rookie Lance Stroll joining for the Brazilian.

Rosberg retired five days after beating team-mate Lewis Hamilton for the 2016 title. Mercedes seemingly want its second driver to be on par with Hamilton so that they can push each other and in order to clinch another constructors' title.

In another development, Mercedes technical director Paddy Lowe is said to be close to moving to Williams.