Former F1 racer Christian Klien says the current state of the F1 driver market is an indication of the struggles facing teams in the search for finance.

Force India and Caterham both have vacancies for the year ahead while Marussia is now also looking to finalise its driver line-up after splitting with Timo Glock earlier this week.

Marussia has openly said that the decision to split with Glock was affected by 'tough economic conditions', while it would appear that a lack of financial backing is also working against Heikki Kovalainen when it comes to staying with Caterham for another year.

Writing in a column on Pitpass, Klien admitted that the situation with both outfits was an indication of how teams are now being forced to take drivers based on money rather than results - arguing that he would retain both Glock and Kovalainen if he had been in charge.

"It seems a bit of a mess at Caterham, but I think it is because everyone is struggling for money," the former Red Bull man said. "Marussia has shown that in recent days with Timo Glock, who is a very talented guy, losing his drive because of money.

"I think Heikki Kovalainen is the best driver available on the market, followed by Glock, but neither have any money behind him like others seem to. Kovalainen is a brilliant qualifier, he used to out-qualify Jarno Trulli who was famous for being a qualifying specialist, and is very consistent.

"A team's decision on drivers should be made on results, and Kovalainen and Glock have good records. If I was in charge I wouldn't hesitate in keeping either of them on for another season."

Adding that Force India could 'take more of a risk on a new driver' given it already has the experience of Paul di Resta onboard, Klien said was eager to see Jules Bianchi given his chance in a race seat having previously been test and reserve driver for the Silverstone-based team.

"Adrian Sutil seems to be the favourite but that feels like a backwards step," he wrote. "I'd like to see Jules Bianchi given a chance. Ferrari is looking at helping him find a seat in F1 and I think it would be a shame if that doesn't happen because he's a young guy with a lot of potential."