In reports on Tuesday, Saudi Arabia’s Al Watan and Arab News newspapers did not give the nationalities of the 49 workers, and foreign embassy staff could not immediately provide details.
Al-Watan said an unidentified number were sentenced to four months in prison and 300 lashes for destroying public property and inciting unrest.
Construction sector workers, chiefly at the Binladin Group and another firm Saudi Oger, were left waiting for salaries after a collapse in oil revenues left the Kingdom unable to pay private firms it had contracted.
In May, Binladin Group employees set fire to at least seven company buses in a protest over unpaid salaries and a large round of reported layoffs by the construction giant.
A Binladin Group spokesman could not be reached on Tuesday. But late last year it said it had completed payment to 70,000 laid-off employees.
Workers still with the company would receive their back pay as the government settled its arrears, the company said.