Rupert Murdoch has labelled victims of phone hacking "scumbag celebrities" after they met David Cameron during the Conservative party conference.

On Saturday night Murdoch took to Twitter to criticise the talks in Birmingham between the prime minister and members of the Hacked Off campaign, singer Charlotte Church, former Crimewatch presenter Jacqui Hames and actor Hugh Grant.

Murdoch tweeted: "Told UK's Cameron receiving scumbag celebrities pushing for even more privacy laws. Trust the toffs! Transparency under attack. Bad."

The comments sparked a storm of disapproval, with Murdoch repeatedly asked to apologise for the remarks and remove the tweets. Hames hit back at the head of News Corp, tweeting: "Never let the facts get in the way of a good story eh Rupert. Happy to discuss our concerns with you sometime?". She added: "I've been called worse, but admittedly not by CEO of large multinational corp."

Murdoch replied to Hames, but it was not clear if he was aware who she was as he tweeted: "not referring to these ladies". Thais Portilho-Shrimpton, a journalist and former co-ordinator of the Hacked Off campaign, tweeted that she had set up a meeting "between PM, a former Crimewatch presenter, a singer and an actor", adding: "You must be referring to all".

The former Liberal Democrat MP Evan Harris was one of the first to respond to the comments, tweeting: "By "scumbag celebs" do u mean the WPC u put under surveillance, the teen girl yr papers perved over, or the actor u hacked?". He accused Murdoch of being disingenuous and hypocritical. "I was at meeting & unlike yr secret meetngs w/ PMs promoting yr business, the victims went in front door & told media abt it," he wrote, calling for Murdoch to remove his tweet, labelling him a "bully".

Murdoch also engaged with one Twitter user who said: "Scumbags"? And your journalists and executives are what?". Murdoch replied, somewhat incomprehensibly: "They don't get arrested for indecency on major LA highways! Or abandon love child's".

This encouraged Labour MP and phone-hacking campaigner Tom Watson to wade into the argument . "[B]ut they do blackmail sex workers and forget to make their excuses and leave. And you should talk to Mr M Mahmood," he replied to Murdoch.

The incident was not entirely without humour, however, with one wag tweeting: "The real scandal here is that the head of a news empire can't pluralise the world 'child'".