Alonso fastest during dangerously wet Belgian practice

The 90-minute morning session was blighted by heavy rain and dark skies with conditions so bad that the Formula BMW and GP2 practice periods either side were red-flagged for being too dangerous.

The rain did finally ease off in the closing minutes, during which time Ferrari star Alonso, who had been out in front anyway, extended his advantage over McLaren's Lewis Hamilton.

Although the seven-kilometre Spa circuit was still horribly wet, the double world champion clocked a time just a fraction over two minutes.

The rain then poured down during the two-and-a-half-hour interval before giving way for good shortly before the start of the second session.

As a dry line started to materialise so the times tumbled, with the lead changing hands on several occasions.

With 16 minutes remaining Force India's Adrian Sutil was narrowly out in front, with Hamilton again second at the time.

But then the session was red-flagged, with the message appearing that there 'may be spectators in a dangerous area'.

With four minutes remaining the track reopened, with Alonso at the head of a queue of cars lined up in the pit lane.

With a clear track in front of him the 29-year-old Spaniard deposed Sutil at the top of the standings with a lap of one minute 49.032 seconds, 11 seconds faster than his morning run in the wet.