Two air ambulances were needed to take people to hospital

The south west Wales location of the rally crash

from the scene in the forested 11th stage of the rally in Brechfa, near Carmarthen on Saturday afternoon.

Both police and the rally organisers have launched an inquiry after Sainz slid wide at a corner eight miles into the muddy forest after apparently striking a marshal's vehicle which was parked along the route.

The two-times world champion, who was in fourth place at the time, went on to complete the 18.53-mile stage but has since been pulled from the competition by team sponsors Ford and is said to be distraught at the injuries caused.

In addition to the two seriously injured children, one adult is in hospital with head injuries and another has back injuries, although none are said to be life-threatening.

Dyfed Powys Police in Carmarthen have established a Network Q Rally hotline for concerned friends and family of those who may have been attending the rally. The number is 01267 232000.

Spain's Carlos Sainz moments before he crashed

Rally organisers have made the event all-ticket in recent years to reduce numbers and increase safety, although the use of isolated areas makes it difficult to stop people turning up without tickets.

Spectators are supposed to stand in designated viewing areas but it is not known whether the fans involved in the incident were in such a place or had moved to a more dangerous area to get a better view of the cars as they travel at around 100mph.

The rally, being staged for the 57th time this year, regularly draws around 200,000 fans during the four days.

Sainz's fellow Ford team member, Scotland's Colin McRae, spectacularly crashed out of the rally in a 100mph barrelroll on Friday, leaving the title open to England's hopeful Richard Burns.