BAKU (AFP) - Lewis Hamilton topped the times ahead of Mercedes team-mate and championship leader Nico Rosberg in both of Friday's (June 17) incident-packed practice sessions for this weekend's European Grand Prix in Baku.

The defending world champion made light of the difficulties faced in learning a new street track, but was one of a long list of drivers who went off the circuit and brushed the barriers on a day of accidents, incidents and car failures.

Many of the problems were caused by the track's tricky design and lack of run-off space, but others were due to loose kerbs, most of which had to be refixed between sessions on a warm and overcast afternoon.

The track, described as dangerous in places by many drivers, including 2009 champion Jenson Button of McLaren and Rosberg, claimed many victims who struggled with the dusty surface and tight turns lacking broad run-off spaces.

Australian Daniel Ricciardo provided the most spectacular incident of the day when he crashed at Turn 15 in the opening session, which was red-flagged to clear the track. His Red Bull was repaired and he rejoined in the second practice.

The second session ended with Hamilton, who has trimmed Rosberg's lead in the title race from 43 points to nine in the last month, fastest in one minute and 44.223 seconds, ahead of Rosberg by seven-tenths of a second. Third was Mexican Sergio Perez of Force India.

Finn Valtteri Bottas was fourth for Williams ahead of German Nico Hulkenberg in the second Force India.

Sebastian Vettel just made the top 10, the four-time champion ending his day cruising back to the pits slowly as the Ferrari team diagnosed mechanical problems for both of their cars.