They also dismissed speculation that Thomas Hughes, 29, had been attacked by fellow lags. The Ministry of Justice (MoJ) said it was “not true” that any attack had taken place.
An MoJ spokesperson told BirminghamLive: “We checked with the prison governor and there’s been no assault or injuries.”
Hughes, from Shirley in Solihull, was convicted of his six-year-old son’s manslaughter and is currently serving at least 21 years for his crimes.
His ex-partner Emma Tustin, 32, was convicted of Arthur’s murder after he died at their home in June 2020.
She was also found guilty of multiple counts of cruelty – including salt poisoning – and was jailed for life with a minimum term of 29 years.
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Arthur’s mum Olivia Labinjo-Halcrow, who herself is in jail for stabbing her partner to death, was finally given permission to bury her son last month.
A man called Daniel claimed to be Hughes’ brother reportedly revealed the latest cruel twist on the Arthur’s Voice Facebook page.
According to the Sun, he wrote: “Today was a new low. Today, my family and I were informed we will not be allowed to attend the funeral.”
He lashed out at the maternal side of the family for “trying to have a funeral without telling us”.
He added: “We will not ‘gatecrash’ Arthur’s funeral, it could lead to a scene and that beautiful little boy deserves only the best send off.
“It’s not a pick a side situation. There are no sides.
“There is only Arthur. Maternal and paternal families grieve for him.”
During the trial, it emerged that Arthur’s uncle was threatened with arrest when he attempted to flag his concerns about the youngster to police.