The 33-year-old musician reached a settlement with the band this week after they alleged his 2016 single 'Say You Won’t Let Go' - which has racked up 1.8billion Spotify streams - was similar in composition to their 2008 track 'The Man Who Can't Be Moved', taking legal action.
Arthur has now hit out at the band - fronted by Danny O'Donoghue - accusing them of taking credit where none is due.
In a Twitter post, he said: "Where there’s a hit there’ll be a bunch of greedy b****, egomaniac vultures like the script (sic)"
The Script members Danny and Mark Sheehan are now formally listed as songwriters on the song.
James has insisted his track "was a completely original idea" and accused the band's lawyer of using "very dirty tactics" while claiming he only accepted the settlement because of the high cost of legal fees.
On Twitter, he alleged: "I can sleep at night knowing that ‘Say You Won’t Let Go’ was a completely original idea and every single musicologist in the UK said there was no case and threw it out.
"The script then pursued the case in the US with a lawyer that employs very dirty tactics.
"The only reason I had to settle back then was because I couldn’t afford the legal fees in America at the time and they knew that, as we were on the same management.
"Of course they didn’t want any details spoken about publicly as part of the deal. (sic)"
And James - who has criticised the group over the lawsuit in the past - reiterated his stance as he insisted they had "nothing to do" with his hit single.
He added: "Congrats on stealing a percentage of a song you had nothing to do with."
The terms of the settlement are not known, but the Daily Mirror reports that the lawsuit - which was filed in 2018 and handled by their lawyer Richard Busch - claimed the song made James £14 million.
They demanded "all streaming, distribution, publishing and touring revenue connected to the song", plus statutory damages.
James hit out at supposed similarities between the two tracks the previous year, saying: "It's 2017, there's only seven notes in music.
"Every blues song sounds the f****** same. People get wound up about these things for no reason."
Sheehan previously insisted there were no hard feelings on their part, and hailed James as a "fantastic artist".
He said: "The thing about these things is everyone gets into a ‘he said, she said’ thing, and we don’t want to put James down.
"I don’t want anyone to put us down, so you’ve got to protect everybody’s career. We think James is a fantastic artist."
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