Motor racing-Force India to take more risks with fourth place secure

(Adds Russell to take part in practice at next races)

LONDON, Nov 7 (Reuters) - Force India are prepared to let Sergio Perez and Esteban Ocon race more freely in the last two races of the season now that the team are sure of fourth place in the Formula One championship, co-owner Vijay Mallya indicated on Tuesday.

Mexican Perez and his young French team mate were reined in by the Silverstone-based team after their on-track clashes cost Force India points and possible podium places earlier in the year.

The team also announced that 19-year-old Briton George Russell, who won this year's GP3 series and is backed by champions Mercedes, will take part in Friday practice in Brazil this weekend and Abu Dhabi later in the month.

Force India, who use Mercedes engines, are now 99 points clear of fifth-placed Williams, and 165 behind third-placed Red Bull with a maximum 86 remaining to be won.

"With fourth place secure, we have the freedom to take a new approach into the remaining races -- perhaps by trying some different things or different Friday drivers in the car to see what we can learn for next year," said Mallya in a team preview for this weekend's Brazilian Grand Prix.

"We can also be more aggressive with strategies and take more risks," added the tycoon, who is contesting an extradition request from India on fraud charges and has not left Britain since March last year.

"We're still hungry for strong results and want to end the season on a high note. The race in Brazil this week is an opportunity to continue our run of strong performances at the very least."

Force India, who finished fourth overall last year with 173 points, are enjoying their best season yet in terms of points scored with 175 from 18 races so far.

Perez finished fourth at a wet Interlagos last season, while Ocon -- then with now-defunct Manor in his debut season -- was 12th.

Force India have previously given Mexican reserve driver Alfonso Celis Jr some of their Friday morning practice slots.

Russell will take Perez's car in first practice in Brazil and Ocon's in Abu Dhabi. (Reporting by Alan Baldwin, editing by Pritha Sarkar and Toby Davis)