Press regulation: MP Roger Williams to back legislation
A Welsh Liberal Democrat MP says he will be voting against Prime Minister David Cameron's plans for press regulation without legislation.
Monday's Commons vote is expected to be close, and Mr Cameron may be defeated.
Brecon and Radnor MP Roger Williams says legislation is necessary to protect victims of press intrusion.
But Conservative Montgomeryshire MP Glyn Davies said a "civilised, democratic society" depended on freedom of speech and of the press.
The vote comes after Lord Justice Leveson's inquiry into press ethics.
It was sparked by revelations of the illegal practice of phone hacking by journalists, which let to the closure of the News of the World in 2011.
Leveson found newspapers had "wreaked havoc with the lives of innocent people" under the existing regime of self-regulation.
He called for a new, independent regulator backed by legislation designed to assess whether it is doing its job properly.
On Thursday, Mr Cameron called time on cross-party talks on the reforms and instead published plans for a royal charter to establish a tougher press regulator.
Mr Cameron said he believed enshrining legislation in law will harm press freedom. But the Tories' coalition partners the Liberal Democrats have joined with Labour to publish rival plans.
They insist that a royal charter should be backed up by law as the rules would lack impact without it.
Speaking on the Sunday Politics Wales programme, Mr Williams said Mr Cameron was right to bring the issue of press regulation "to a head" but he would be voting against his plan on Monday.
"I think he's bringing the wrong proposals forward - we need something stronger based on legislation because that's the only thing that the public really want," he added.
Mr Williams said newspapers had had self-regulation for a long time and their code of conduct was out of date.
"Not only did they not look after the code properly, they allowed a culture which allowed the press to believe that they could break the law with impunity.
"They could hack people's phones. They could bribe public officials to give them information. That can't go on any longer and that's why it has got to be underpinned by law."
Former Plaid Cymru leader Lord Wigley told Sunday Politics that he hoped to speak against Mr Cameron's plans in a House of Lords debate on Monday.
"If [a royal charter] is in law then any changes have to go through Parliament," he added.
"It's not a matter of Parliament telling the media what to do, it would ensure that the media can't restart the difficulties that we've had over recent years - that has got to be put away for ever."
Paul Flynn, Labour MP for Newport West, said the argument for freedom of speech had been abused by newspapers, saying it was a "freedom to lie and to criticise people who were innocent of any action".
"It will be a vote tomorrow to see whether we're going to have a tough independent watchdog or whether we're going to have a new pussy cat without teeth or claws."
But Glyn Davies, Conservative MP for Montgomeryshire, said it was important to preserve freedom of speech.
"Civilised, democratic society depends on freedom of speech, which in turn depends on freedom of the press," he said.
"That doesn't give the press the right to break any laws. It has to stick within the criminal law.
"I think we have seen a reluctance of the police to take the press on, which has, I think, maybe led to a huge amount of disillusionment with the position."