Orbán acknowledged a debate that had emerged over the legal scope of the president's power to issue pardons and pointed to the need to "clarify the situation with a plain and unambiguous decision".

"On behalf of the government, I've submitted an amendment to the constitution that would preclude pardons in the case of crimes against minors," he said.

President Katalin Novák has recently come under criticism for an earlier pardon issued to a man convicted as an accomplice in a child sexual abuse case.

The Sándor Palace said the president would "gladly sign" the amendment offering stronger protection for children after it was approved by lawmakers.

Máté Kocsis, who heads the parliamentary group of governing Fidesz, told public radio on Friday that the party's MPs backed the bill submitted by the prime minister. "This loophole must be closed," he said on Kossuth Radio.

He said nobody questioned the legality of the president's decision on the pardon, but suggested that it would be good to address the motivation for the decision sometime. It's not the job of MPs to discuss the basis of the decision, but to ensure that something like this never happens again, he added. 

MPs could vote on the amendment in the second half of March, he said.