Mr Hicks said his son was unable to communicate properly during their last telephone conversation in July this year.
He was now convinced his son was suffering severe mental problems, exacerbated by spending the past nine months in solitary confinement.
"We have been worried about David's mental state for three years," Mr Hicks said.
"This shows he's not as well as everyone says he is.
"He has probably thought 'do I need to go through this mental stress' and speak to the family.
"The Australian government says he's OK ... but they're cold, they have got no heart, they don't care about him."According to another report in The Age the Federal government will question a decision to ban forensic psychiatrist Professor Paul Mullen from visiting Hicks at Guantanamo Bay.
Given the government's record of equivocation on all Hicks related matters I'd be surprised if the questioning was very robust. It seems that those who want to see the matter resolved are being fobbed off with bureaucratic waffle which appears to hold out a slight chance of a resolution while preserving a ruthless and immoral status quo.
There are some, such as Mirko Bagaric, who criticise people like me for focusing on David Hicks to the exclusion of the other Guantanamo detainees. I take their point, but justify my position by saying that the Hicks situation is different because he, like me, is an Australian citizen and therefore deserves the protection of our legal system. Once this has been given I'll turn my attention to the remaining detainees (and other persons who have been detained without trial).