Formula One will outlaw traction control systems and automatic gearboxes from the British Grand Prix on July 20, the sport's governing body has announced.

But drivers will still be able to communicate with their teams after the International Automobile Federation (FIA) went back on an earlier plan for the immediate elimination of pit-to-car radio.

"Traction control and automatic gearboxes will no longer be allowed from half way through the season -- i.e. from the 2003 British Grand Prix," the FIA said in a statement on Tuesday.

"Launch control will end at the same time, provided the teams can all operate their current clutches manually."

The final ruling on traction control fell halfway between the FIA's desire to ban so-called 'driver aids' from the start of the season on March 9 and the opposition of some teams to any change until 2004 at the earliest.

The FIA had announced sweeping changes last week to cut costs and liven up racing after a difficult year that has seen two teams, Prost and Arrows, put out of business.

But they modified the initial measures after FIA technical delegate Charlie Whiting met team technical heads on Friday and then independent electronics specialists and the teams' own experts on Tuesday.

Traction control, which reduces wheelspin and makes cars easier to drive in the wet, was banned from the end of 1993 to 2001 when it was reinstated after the FIA recognised difficulties in policing the systems.

"We are now very confident in our own ability to police these new measures on traction control and launch control with new technology and additional FIA sensors," an FIA spokesman said.

A $1 million (620,000 pounds) reward for anyone providing proof of a team cheating after the ban comes into force remained on offer, the spokesman added.

The main changes concerned the use of the spare car, team-to-car radio communications and procedures following the new one-lap qualifying format.

The FIA said the radio would be allowed, provided it was a stand-alone system and could not transmit other data. The communications must also be open and accessible to the governing body and broadcasters.

"The possibility of a standard system accessible to the public at a Grand Prix is being explored," it added.

The FIA said that pit-to-car telemetry, the systems enabling engineers to change settings while a car is out on the track, would go from the start of the season on March 9 while car-to-pit systems would remain until 2004.

It said this was because an immediate ban on the latter, originally intended, would not save money because the data acquisition systems could not be eliminated from cars in the short amount of time now available.

The rules on spare cars were relaxed but teams will still be allowed to use one only if a driver's race car is damaged beyond repair.

"If a race car fails just before the start, any spare car will start from the pit lane, as will a spare car used following a race stoppage in the first two laps." the FIA said.

Cars will be held in 'Parc Ferme' conditions between qualifying and the race but they need not be parked in the usual open area at circuits where FIA scrutineering takes place.

Instead, they can be kept in team garages under strict supervision.

"Any work other than a very restricted list will require special authorisation," the FIA added.

Other proposed changes to be introduced from 2004, mainly controversial ones governing engines that some manufacturers have already rejected, remained subject to the agreement of Formula One's technical commission.