Ken Corsar, director of education, admits the new figure of 9 per cent unauthorised absence at Victoria Drive Secondary is probably the "closest to the truth". Previously it was 1 per cent. If all city schools were to take the same hard line their returns might also rise.
Peter Mullen, the Roman Catholic Church's representative on the city's education committee, said the figures were "frightening beyond belief" but Mr Corsar assured him that staff were trying to get parents involved in dealing with the problem.
Mr Mullen said that at one time shopkeepers in Rothesay would telephone the local academy if they saw pupils in the street during school hours. The result was near perfect attendance. Mr Corsar said if the same thing happened in Glasgow shop managers in the St Enoch Centre would "be spending all their time phoning schools".
He warned: "We have to make it clear that attendance is not a take it or leave it issue. We have to address the parental role."
Figures show that authorised absence in secondaries ranges from 10 per cent to 27 per cent and unauthorised absence from zero to 9 per cent. In primaries, authorised absence ranged from 3 per cent to 14 per cent and unauthorised absence from zero to 5 per cent.
Chris Mason, the Liberal Democrat leader, said he was concerned there was to be a further reduction in the number of school attendance officers but he was assured it was only in area supervisors.
Councillors have backed a strategy which focuses on encouragement for parents, the needs of school "phobics" and the reintegration of pupils with long-term attendance problems.