A state agency that provides low-interest mortgages is foreclosing on a small number of clients even though they are making their monthly payments, a state Senate watchdog group reported.

The California Housing Finance Agency is foreclosing on homes because their financially strapped owners temporarily rent them out and move into cheaper rental properties, the Senate Office of Oversight and Outcomes said Monday.

The agency, which finances the mortgages through the sale of tax-free bonds, allows borrowers to rent their homes only if they suffer a severe economic hardship, such as losing a job.

That tight restriction was recommended to the agency by its bond counsel prior to the collapse of the state's housing market and the deep recession of 2007-09.

About 350 Housing Finance Agency borrowers rented their homes without permission and 21, so far, have been foreclosed on. Another 186 are being threatened with foreclosure despite staying current on their monthly loan payments, the oversight office said.

According to the report, the agency said it didn't know how many borrowers were denied permission to rent.

The agency did not respond to requests for further comment.