Pirelli has agreed to tweak one of their tyre compounds following a turbulent start to the new Formula One season.

The Italian company's range of rubber for this year has dominated the sport, with the likes of Red Bull particularly outspoken, despite two wins from the opening four races for Sebastian Vettel.

Even following Vettel's victory in Bahrain on Sunday, team principal Christian Horner still described the tyres as "too on an edge" and "very complex".

But Pirelli, after evaluating tyre performance over the balance of the first four races, have only decided to alter the hard compound for the remainder of the season.

Pirelli motorsport director Paul Hembery said: "In consultation with all the teams we have taken the decision to change the hard compound from Spain (May 10-12) onwards.

"That was as we did in Barcelona two years ago when we also introduced a new hard tyre for the rest of the season.

"This latest version of the hard compound is much closer to the 2012 tyre, with the aim of giving the teams more opportunity to run a wider range of strategies in combination with the other compounds, which remain unchanged."

At Barcelona's Circuit de Catalunya the teams will use the hard and medium compounds; in Monaco they will have the soft and supersoft available, whilst in Canada it will be the medium and supersoft.