Lewis Hamilton topped the timing sheets at first practice in Bahrain, setting a 1m33.572 with the reigning two-time world champion Sebastian Vettel three tenths behind him in second place.

Putting aside the political controversy and news that two of his mechanics requested to fly home early from Bahrain, Force India's Paul di Resta posted the third-fastest time of the morning session, with a 1m34.150.

The two mechanics left Bahrain to fly back to Britain on Thursday after one of them - along with three others - was caught up in a clash between police and protesters involving Molotov cocktails and tear gas canisters.

Despite the troubles, it was a good session for the Force India team, with Nico Hulkenberg in the sister car setting a 1m34.344 which was good enough for sixth place.

Force India did say after, however, that the team might not take part in the afternoon session so they can pack up and leave the track early to avoid getting caught up in violent protests again.

Hamilton's team-mate Jenson Button finished fifth with a 1m34.277, half a tenth behind the winner of last weekend's Malaysian grand prix, Nico Rosberg in the Mercedes AMG.

His Mercedes team-mate seven-time world champion Michael Schumacher came seventh 1.5 tenths behind in a Mercedes car that has proved to be a creditable competitor for McLaren and Red Bull.

Ferrari's poor performance seems to have followed them to Bahrain, with Fernando Alonso managing only the 13th-fastest time of the Friday morning session, a 1m35.436 - and team-mate Felipe Massa finished two places behind, setting a time of 1m35.719.

Mark Webber finished in eighth with a 1m34.552, one place and half a tenth ahead of Kimi Raikkonen in the impressive Lotus.

Unofficial results are below:
Pos Driver Team Time Laps
1. Lewis Hamilton McLaren-Mercedes 1m33.572 11
2. Sebastian Vettel Red Bull-Renault 1m33.877s + 0.305 21
3. Paul di Resta Force India-Mercedes 1m34.150s + 0.578 26
4. Nico Rosberg Mercedes 1m34.249s + 0.677 23
5. Jenson Button McLaren-Mercedes 1m34.277s + 0.705 14
6. Nico Hulkenberg Force India-Mercedes 1m34.344s + 0.772 26
7. Michael Schumacher Mercedes 1m34.483s + 0.911 17
8. Mark Webber Red Bull-Renault 1m34.552s + 0.980 22
9. Kimi Raikkonen Lotus-Renault 1m34.609s + 1.037 17
10. Romain Grosjean Lotus-Renault 1m34.847s + 1.275 20
11. Sergio Perez Sauber-Ferrari 1m35.024s + 1.452 22
12. Pastor Maldonado Williams-Renault 1m35.268s + 1.696 24
13. Fernando Alonso Ferrari 1m35.436s + 1.864 21
14. Valtteri Bottas Williams-Renault 1m35.497s + 1.925 24
15. Felipe Massa Ferrari 1m35.719s + 2.147 19
16. Kamui Kobayashi Sauber-Ferrari 1m35.929s + 2.357 24
17. Jean-Eric Vergne Toro Rosso-Ferrari 1m36.195s + 2.623 20
18. Heikki Kovalainen Caterham-Renault 1m36.330s + 2.758 11
19. Vitaly Petrov Caterham-Renault 1m36.484s + 2.912 18
20. Daniel Ricciardo Toro Rosso-Ferrari 1m36.591s + 3.019 20
21. Charles Pic Marussia-Cosworth 1m37.467s + 3.895 17
22. Timo Glock Marussia-Cosworth 1m38.006s + 4.434 18
23. Pedro de la Rosa HRT-Cosworth 1m38.877s + 5.305 19
24. Narain Karthikeyan HRT-Cosworth 1m39.996s + 6.424 23

India