UK retailers are being urged to increase the age at which alcohol buyers are asked for ID from 21 to 25.

The Retail of Alcohol Standards Group (RASG) said the Challenge 21 initiative, which encourages shop staff to ask for ID from anyone who appears to be under 21, had led to a “marked reduction” in under-age purchases.

The new Government-backed Challenge 25 scheme, which has already been adopted by some retailers and is being promoted nationally in a campaign launched this week, would combat proxy purchase by young adults for underage friends, said supporters.

While acknowledging the success of Challenge 21, Home Office Minister Alan Campbell called on retailers to switch to Challenge 25.

“We recognise that the majority of retailers take their responsibilities seriously, refusing to sell alcohol to about 1.5 million children every month, and we are determined to continue working with them to tackle the problem,” said the minister.

It was time for retailers to go a step further to reduce the levels of under-age purchase, said RASG chairman Nick Grant.

“Feedback from frontline staff suggests they want the freedom to challenge more widely to ensure young people are not breaking the law, whether attempting to purchase alcohol for themselves or for others who are under 18,” he said.

The suggested increase in age limits was also welcomed by the Association of Chief Police Officers.

“It is interesting that senior figures from the industry have been pre-briefed and have given it their full and practical support,” said its licensing spokesman, Simon O’Brien.

“It has come without prompt. This is a sign of the determination from those involved in the sale of alcohol to work towards the common goal of safe and sensible alcohol consumption.”

The RASG will recommend the Challenge 25 scheme to its members, which include the ACS, Tesco, Asda, Sainsbury's, Morrisons Waitrose, Thresher, Oddbins, ­One-Stop, Somerfield, Spar and Bargain Booze.