Piers Morgan has responded to the claim that he told Jeremy Paxman how to access people's voicemail messages, branding him an "ungrateful little wretch".
Writing on his Twitter page, Mr Morgan said: "Right - that's the last time I'm inviting Jeremy Paxman to lunch. Ungrateful little wretch."
The Leveson Inquiry had earlier today heard that Daily Mirror former editor Mr Morgan once told Jeremy Paxman how to access voicemail messages.
Newsnight anchorman Mr Paxman said he attended a lunch at Mirror headquarters in Canary Wharf in September 2002 where Mr Morgan teased Ulrika Jonsson about her relationship with former England football manager Sven-Goran Eriksson, saying he knew about a conversation they had.
Mr Paxman said Mr Morgan explained to him how to access people's phone messages after teasing the Swedish television presenter about the conversation.
Mr Paxman told the inquiry: "He turned to me and said 'Have you got a mobile phone?'
"I said yes and he asked if there was a security setting on the message bit of it. I didn't know what he was talking about.
"He then explained the way to get access to people's messages was to go to the factory default setting and press either 0000 or 1234 and that if you didn't put on your own code, his words, 'You're a fool'."
The BBC Newsnight presenter said he remembered the lunch for two reasons: he wondered why he had been invited and because of what Morgan said.
"Mr Morgan was teasing Ulrika that he knew what had happened in a conversation between her and Sven-Goran Eriksson," said Paxman.
"I don't know if he was repeating a conversation he had heard or he was imagining this conversation.
"To be fair to him I should imagine both possibly because he probably was imagining it."
Paxman said Morgan put on a funny Swedish voice.
"It was a rather bad parody."
He added: "I don't know if he was making this up, making up the conversation.
"But it was clearly something he was familiar with and I wasn't.
"I didn't know that this went on."
The veteran presenter said Morgan's treatment of Jonsson was close to bullying.
"I didn't like it," he said.
Morgan, who now has his own chat show for CNN in America, appeared by video link at the hearing in December last year.
At the time details from the lunch had not emerged but he told the inquiry he was "still very proud of a lot of the very good stuff that both the Mirror and the News of the World did during my tenure as editor".
Tomorrow, Culture Secretary Jeremy Hunt's former special adviser Adam Smith will give evidence to the Leveson Inquiry.
News Corporation lobbyist Frederic Michel will also appear.
Mr Smith resigned last month over his dealings with Mr Michel in relation to the BSkyB takeover bid.
Their evidence will lead to fresh scrutiny of Mr Hunt's role in the process.