Turkey's parliament has rejected an opposition motion for an inquiry into allegations that President Recep Tayyip Erdogan's family members have evaded taxes by transferring millions of dollars to off-shore accounts.

The main opposition Republican People's Party, or CHP, says it has obtained documents showing that family members sent up to $15 million dollars to the Isle of Man, and requested a parliamentary investigation.

Parliament, which is dominated by Erdogan's ruling-party members, rejected the motion Thursday.

Erdogan has denied the allegations, said the documents are fakes, and insisted that "not a cent" was sent. He has filed a lawsuit against the CHP's chairman.

On Thursday, the Ankara prosecutor's office said it was launching a probe and would request the documents. The CHP says however that the issue is ethical, not criminal.