As ever, information is difficult to come by, but it seems as if the president of Mongolia, Tsakhiagiin Elbegdorj, has vetoed a bill.
According to Mongolia Economy and Finance, in March President Elbegdorj vetoed the Law on regulating public and private interests in the public service and preventing conflicts of interests. The report also states that he partially vetoed the bill in February.
Art. 33 of the constitution states that the president has the power: “to exercise a right to veto against all or part of laws and other decisions adopted by the State lkh Khural. The laws or decisions shall remain in force if two thirds of the members of the State Ikh Khural present in the session do not accept the President’s veto”. So, partial vetoes are a possibility.
All of that said, I have not been able to corroborate this story from another source.