Sebastian Vettel has admitted he is worried about the "pay driver" issue in formula one.

The global economic situation has led to an increase in the number of drivers who bring substantial financial backing to their teams.

World champion Vettel said on Austrian television Servus TV that the situation is compromising the quality of the F1 grid.

"There is a risk to us if the drivers being lapped are unpredictable," answered the German when asked if the pay-drivers are dangerous.

"There are some in the field that we know are moving obstacles," added 23-year-old Vettel.

Complicating the issue, he said, is that the return of KERS and the debut of moveable rear wings causes drivers to take their eyes off the track.

"It’s a bit like driving a car while playing with your mobile phone," said the German.