Alastair Stewart reportedly left ITV News after using the term "angry ape" in a Twitter row.
The 67-year-old broadcaster stepped down after what he described as a "misjudgment", and it\'s said his departure saw him breach ITN editorial guidelines in a social media spat with a black man.
During a row with Twitter user Martin Shapland - as the pair were debating the funding of the Royal Family earlier this month - Alastair quoted William Shakespeare\'s \'Measure for Measure\'.
He tweeted: "But man, proud man, Dress\'d in a little brief authority. Most ignorant of what he\'s most assur\'d, his glassy essence -- like an angry ape."
Shapland responded: "Just an ITV newsreader referring to me as an ape with the cover of Shakespeare. Measure for measure, Alastair is a disgrace."
A source told The Sun newspaper: "The feeling is it was a poor call for Alastair to get involved in this sort of exchange at all.
"The use of the word \'ape\' is a major error even when quoting from Shakespeare."
In a statement this week, Alastair - who has now deleted his Twitter account - said: "It was a misjudgment which I regret, but it\'s been a privilege to bring the news to households throughout the UK for the past 40 years."
An internal email from ITN informed their staff members that the decision, which was backed by ITV, followed behaviour that breached editorial guidelines.
Michael Jermey, ITV director of news and current affairs, said in a statement: "Alastair has been a long-standing, familiar figure to viewers of ITV News, both reporting and presenting with distinction. We wish him the very best for the future."
Whilst ITN\'s chief executive Anna Mallett added: "We would like to recognise Alastair\'s contribution as one of the UK\'s foremost journalists and TV presenters and to thank him for his commitment to delivering high-quality broadcast news over many years."
Alastair first joined ITN in 1980, acting as one of ITV\'s flagship newsreaders for more than three decades, and becoming the longest-serving mail newsreader on British television.
The presenter received an OBE (Order of the British Empire) for services to broadcasting and charity in 2006.
