Pirelli will supply Formula 1 teams with an extra set of tyres for practice sessions at this weekend's Spanish Grand Prix.

The idea is to ensure leading drivers run for the entire session rather than waiting for others to clean the track and make it more suitable for effective running.

The genesis of the plan was to make the tyres available only for rookie, non-race drivers to help them gain experience.

But this has been abandoned in favour of all drivers getting the extra set.

Pirelli said the additional tyres would be of a "prototype hard compound".

Initially, the plan is only in place for the Spanish Grand Prix. Pirelli said it would see if it ensured teams spent longer on the track before making a decision on the rest of the season.

Pirelli has already announced it has made a small tweak to the regular 'hard' compound tyre for the Spanish race, which will make the rubber slightly more durable and lower its operating temperature.

However the firm has resisted pressure from world champions Red Bull to make all its tyres more durable in the wake of concerns drivers were not able to push to the limits of the car throughout a race distance for fear of using the tyres up too quickly.