City restaurants were applying surcharges of up to 20per cent during the Easter long weekend.

But the Hospitality Workers Union is worried operators may not be passing the surcharges on to their workers. The Workplace Ombudsman yesterday warned the local industry it would be targeting establishments that failed to pay young workers public holiday penalty rates.

The federal agency last month highlighted a Canberra pub that had to provide back pay totalling $14,000 to 29 of its workers after an investigation by the Workplace Ombudsman discovered they were underpaid. Workplace inspectors discovered the pub was underpaying its workers during a blitz on the Canberra liquor and hospitality industry earlier this year, which saw 51 businesses audited.

In another case discovered last month, the ombudsman found that a fast-food worker had been paid a flat rate of just $15 per hour for working weekends and holidays over the Christmas and New Year period.

A Workplace Ombudsman spokesman said inspectors were worried about workers being underpaid by employers who flouted award conditions.

''The Federal Workplace Ombudsman regularly receives complaints from workers who have been underpaid the penalty rates they are entitled to for working overtime, weekends and public holidays.'' the spokesman said. ''In many situations, hospitality industry workers are entitled to receive penalty rates for working on public holidays, though this will not always be the case.''

The agency said it would target Canberra employers who failed to issue payslips to workers or who did not keep proper time-and-wages sheets.

It encouraged workers to report any abuses.

An Office of Regulatory Services spokeswoman said yesterday that restaurants were free to impose a surcharge of their choice on Sundays and public holidays.