Search warrants have been issued as part of the RCMP's criminal investigation of Sen. Mike Duffy, CTV News has learned.

Sources say the search warrants were recently filed in the Ottawa courthouse.

But the judge who granted the warrants also issued a sealing order. That means details of what the RCMP are looking for will be kept under wraps.

Sources say the search warrants would allow the Mounties to search Duffy's Ottawa-area home and his cottage in P.E.I.

The RCMP is also expected to get a production order to search Duffy's Senate office.

When asked if the RCMP had met with him Thursday, Duffy said: "It would be inappropriate for me to offer any comment."