The Scottish National Party has warned that pupils' lives could be at risk because 14 authorities no longer give primary children swimming lessons during school hours.
Statistics from the Royal Society for the Prevention of Accidents show a 50 per cent rise in deaths by drowning among young people, party activists said last week at their annual conference in Dundee.
Only the more advantaged children could afford to pay for swimming lessons outside school, said Kay Ullrich, the Nationalist MSP, who initiated the campaign for curriculum swimming.
She said a study in Aberdeen had shown low levels of competence in the water among disadvantaged children. One in four could not swim 25 metres after they left primary school, compared to one in 100 from more prosperous homes.
Ms Ullrich, a former swimming instructor in Ayrshire, last session asked the question in Parliament that forced the Scottish Executive to launch an audit of school swimming, which is now underway. She wants parity with England, where every pupil is expected to swim 25 metres by the age of 11.
Audrey Doig, a sports and leisure worker in Renfrewshire, said one in three children could not swim at the age of 10 before they joined the council's swimming programme. One in 10 had never been in a pool before.