Up to 13 employees — who all work at primary and secondary schools in the area — have been asked to stay away from work while an investigation gets underway.

The jannies — employeed by facilities management firm Amey — have been accused of either falsifying timesheets or leaving work earlier than they were supposed to.

However a source said that one worker had been suspended for leaving work early — despite having worked through his lunch.

Police have not been called in however management firm Amey, who won a contract to cover Renfrewshire schools in 2005, said they are working closely with the council on the probe.

An Amey spokeswoman said: “Amey delivers facilities management services to both primary and secondary schools on behalf of Renfrewshire Council.

“We take any allegations of this nature extremely seriously and we are currently conducting a full investigation.

“All employees working within the schools are trained to the required standards and are fully qualified to carry out their roles.

“We remain committed to ensuring high quality services are delivered across all sites and can confirm that service levels are unaffected by the investigation.” Renfrewshire Council said the janitors were not council staff, so they would not have anything to do with the disciplinary of the workers.

A spokesman added: “We are aware of the situation and have liaised with schools and sought and received assurances from Amey that standards and services are being maintained.”