Seattle police are investigating allegations of wage theft by subcontractors on city-funded housing projects.

The evidence of inadequate payment of wages was uncovered in August and September on two city housing projects under construction. Since then, similar allegations have been made on two additional housing projects.

The city, with publicly approved levy funding for affordable housing, contracts construction to nonprofit housing providers. Those nonprofit groups in turn hire contractors, who hire subcontractors to complete the work.

Mayor Mike McGinn on Monday said it was “absolutely abhorrent” for contractors to withhold wages or accept kickbacks in exchange for employment. Because the cases are under investigation, he said he couldn’t say how much money is alleged to have been stolen or which contractors are suspected of illegally withholding wages.

The city uncovered the questionable payments during routine monitoring of contracts on city-financed affordable-housing projects. In 2007, the city began visiting job sites to interview workers and reviewing daily sign-in sheets, certified payrolls and other records.

In 2011, the City Council adopted a wage-theft law protecting workers and strengthening penalties for employers who commit wage theft.

Councilmember Tim Burgess, who sponsored the legislation, said Monday, “The allegations of wage theft on city-financed projects must be taken seriously and investigated thoroughly.”

Lynn Thompson: lthompson@seattletimes.com or 206-464-8305.

On Twitter:@lthompsontimes