Police have said almost two-thirds of off licences tested over three days sold alcohol to people who were under-age. The exercise was carried out as part of an operation by Sussex Police to cut violent crime in public places.
Out of 28 off licences visited by trading standards officers and police, 19 are alleged to have sold alcohol to 'test purchasers' aged under 18.
The premises ranged in size from corner shops to large supermarkets, a spokeswoman for Sussex Police said.
'Not acceptable'
The area targeted between Monday and Wednesday included Eastbourne, Lewes and the Wealden district.
Superintendant Grenville Wilson, of Sussex Police, said: "There is a general correlation between under-age drinking and a tendency to commit crime in later life.
"Working with our partners in trading standards, we have uncovered some potentially serious issues involving some licensed premises.
"Almost two thirds of all those premises we visited sold alcohol to individuals who were under-age.
"This is not acceptable and trading standards officers are now making further investigations about the alleged offences."