TOURISTS and other road users will be confused by a new lower drink- driving limit for Scotland, and ministers could be forced to signpost every cross-border road to warn drivers from England, according to the country's top police officers.

The Association of Chief Police Officers in Scotland (Acpos) says the imminent change will need to be accompanied by a significant public information campaign to warn drivers that Scotland and England will be subject to different limits.

The police said the move will also mean more arrests, divert scarce resources, lead to unemployment for those caught, and have a "potential impact on tourism and the licensing trade".

They also predicted a dramatic rise in cars seized from drunk drivers, as forfeitures apply to those three times over the limit, a reading they say will "not be uncommon" in future.

Justice Secretary Kenny MacAskill has already announced plans to lower the drink-driving limit from the UK measure of 80mg of alcohol per 100ml of blood to the European norm of 50mg/100ml, the equivalent of one pint of beer.

The power to change the limit was devolved by Westminster in last year's Scotland Act.

Despite repeated calls to adopt the European limit, Westminster has so far ruled out a change in England and Wales.

A recent Scottish Government consultation on the plan received overwhelming support from about 50 organisations and almost 70 individuals, with only a handful opposing the change.

However, in its submission, Acpos flagged up a series of practical problems for the police.

"Different road traffic laws across the UK may be confusing to road users, especially tourists," Acpos said, while still backing the 50mg limit. "There is every probability that a reduction in the limit would bring about more convictions ... and undoubtedly more 'morning-after' detections."

The country's leading accident charity called for borderline drunk-drivers to escape with shorter bans if the limit is lowered.

The Royal Society for the Prevention of Accidents (Rospa) said those caught with a reading of between 50mg and 80mg should be disqualified for six rather than 12 months "to encourage public acceptance of the new limits".

Among the handful of respondents opposed to a 50mg limit, one said the move would be "disastrous" to tourism in the Highlands and Islands. Several individuals and groups said the limit should be cut further, to zero.

A Scottish Government spokeswoman said it would respond formally to the comments before Easter. "There are a number of issues to consider fully before a lower limit can be introduced such as how motorists driving into Scotland from England will be made aware of the lower limit," she said.

"Awareness-raising is important, but we are clear that motorists have a responsibility to be aware of the laws of the land in which they are driving."