Sydney shock jock Ray Hadley has taken aim at former Liberal prime ministers John Howard and Tony Abbott over their show of support for George Pell in the wake of his conviction for child sexual abuse, declaring they had made "gross errors of judgment".

In an excoriating attack, Hadley accused the two former prime ministers of showing "a complete lack of understanding" of the victims of paedophiles, and implied Mr Abbott's actions could cost him his seat in Federal Parliament at the election.

Unimpressed: Sydney shock jock Ray Hadley attacked John Howard's "gushing reference". Credit:Louie Douvis

It was revealed in court on Wednesday that Mr Howard provided a character reference for Pell following his conviction in December, in which he praised the cardinal as "a person of both high intelligence and exemplary character".

Mr Abbott phoned Pell on Tuesday when the guilty verdict became public, and told 2GB radio the cardinal remained a "friend". He said it was possible to make "very harsh judgments" on Pell at this time but he would await the outcome of the appeal.