Heikki Kovalainen admits his Formula 1 career may have been cut short because he split with Flavio Briatore.

The now 40-year-old Finn was once one of F1's most promising youngsters, having initially debuted for Briatore-run Renault before being signed by McLaren as Lewis Hamilton's title-winning teammate in 2008.

But Kovalainen then terminated his management contract with Briatore late in 2009, when Briatore was banned from Formula 1 over the 'crashgate' scandal.

"It was the biggest mistake of my career," Kovalainen, who now competes in the All Japan Rally Championship, told Viaplay.

"It would definitely have been worth staying on the same side of the table with Flavio rather than going to the other side of the table," he smiled.

Indeed, his next move after McLaren was to the Lotus-Caterham outfit, which turned out to be one of the slowest on the grid until it collapsed.

"When my McLaren contract was ending and I had to quickly get a new contract, while the drivers managed by Flavio did not have a super license at that point," said Kovalainen.

By 2010, Briatore's Formula 1 ban was lifted.

"If I had just waited until January of the following year, Flavio would have had his punishment reversed and he could have returned," the Finn admitted.

"Yes, Flavio could have made better deals for me, and he had made the best deals of my career before that episode."

Kovalainen is now focusing on building up his rallying career, which so far in Japan has been successful.

"I'm 100 percent focused on rallying now," he confirmed. "I enjoy watching WRC - I stay up all night and day watching nowadays."