The government has been defeated in the House of Lords over new pub laws which critics say will allow unaccompanied children of any age into lap dancing clubs and nightclubs.
Children could encourage more sensible drinking, says ministers
The government blames much of the criticism on ignorance of the current laws and says its shake-up of the licensing system will crack down on under-age drinking.
But the Lords voted by 184 to 111 to add a specific clause to the government's Licensing Bill, barring children under-14 from bars, pubs and clubs unless they are with an adult.
Culture Minister Kim Howells said the government would look carefully at the amendment before deciding what to do next.
Ahead of the vote, Tory spokeswoman Baroness Buscombe said the original plans could even have made pubs a "hunting ground for paedophiles".
Existing laws mean that if a licensee agrees, a child aged 14 or over can enter a pub or nightclub as long as they do not consume alcohol.
Lady Buscombe, who was supported by the Bishop of London, the Rt Rev Richard Chartres, argued it was right to encourage family-friendly pubs but the new laws would allow unrestricted access at any time of day or night.
She said: "This bill lumps together supermarkets and lap dancing clubs under the same licensing regulations with potentially disastrous results.
"While it is wholly desirable for children to accompany their parents on family shopping trips, the same legislation enables them to visit a nightclub at three in the morning on their own if they so wish."
The mother of three teenagers issued a stark warning of the possible dangers ahead.
She said: "The government is having to deal with a growing number of paedophiles.
"If this bill goes ahead unchanged, kids will be hanging around pubs which will become a hunting ground for paedophiles."
Lady Buscombe suggested licensees would feel compelled to keep their businesses as unrestricted as possible to stay competitive.
After the vote, Mr Kim Howells told BBC News 24: "We will certainly look at the amendment that has been put down by the opposition.
"We will see if there is any merit in it and if necessary we will make the changes...
"There is nothing to stop a licensing authority under our proposals from saying: this is not a suitable place for children to go, if we are going to give you a licence, you must make sure that children are not going to go in there."
Mr Howells said the bill covered all licensed premises, from pubs to supermarkets, and it was important not to ban children from the wrong places.
People often did not realise the law allowed children aged over five to drink alcohol in pubs - something the new laws would stop, he added.
Tony Payne, chief executive of the Federation of Licensed Victuallers
Associations, said he was disappointed by the defeat.
"I am sad that the people in the House of Lords don't speak to the people on the streets, or they would see the
benefits," he said.
Many landlords had planned to use the change to set rooms aside for youngsters, with soft drinks bars, discos and even computers for homework, he added.
Tuesday's vote is the latest defeat inflicted over the bill, which has yet to be debated by MPs.
Last week, they insisted schools should be excluded from having to apply for entertainment licences amid fears this could affect even nativity plays.
The bill has provoked fears that the rowdiness and vandalism caused by alcohol in towns and cities could get worse if it becomes law.
The measures remove responsibility for licensing from magistrates and give it to local authorities.