Lewis Hamilton continued his dominant form on Friday morning when he topped the times for Mercedes in opening free practice for this weekend's Spanish Grand Prix.

Hamilton, winner of the last three races in Malaysia, Bahrain and China, clocked a fastest lap of one minute and 27.023 seconds in the final minutes of the session at the Circuit de Catalunya.

His friend, former team-mate and fellow-Briton Jenson Button, was second fastest for McLaren ahead of Australian Daniel Ricciardo in the leading Red Bull on a warm, sunny day.

Hamilton's advantage at the front of the field was a luxurious 0.868 seconds on a day when both championship leader and Mercedes team-mate Nico Rosberg and defending champion Sebastian Vettel suffered problems that curtailed their running.

Rosberg suffered from a power-unit problem while fellow-German Vettel pulled up early in the session with electrical problems.

Home hero Spaniard Fernando Alonso was fourth for Ferrari ahead of German Nico Rosberg in the second Mercedes and Finn Kimi Raikkonen in the second Ferrari.

Dane Kevin Magnussen was seventh for McLaren ahead of Venzuelan Pastor Maldonado of Lotus, Mexican Sergio Perez of Force India and Brazilian Felipe Massa for Williams.

Defending four-time world champion German Sebastian Vettel managed only four laps in his Red Bull before stopping out on the track after suffering electrical problems.