Four Britons freed from US custody in Guantanamo Bay are being used in a "silly political exercise for show", a lawyer for two of the men has said.
Ms Christian said Mr Begg wanted to see his father in dignified conditions
Moazzam Begg, Martin Mubanga, Feroz Abbasi and Richard Belmar were held for three years, accused of al-Qaeda links.
Louise Christian, who represents Mr Mubanga and Mr Abbasi, said questioning of the men in Britain did not have "any legitimate investigative purpose".
"All I know is this process is going on for your benefit, the media," she said.
Ms Christian was at London's Paddington Green police station - where all four men are being held - for the police questioning of Mr Abbasi.
Afterwards, she said she was very worried about her client.
"He has an air of unreality about him. He doesn't know where he is," she said.
"Like all victims of torture he's finding it difficult to talk about it."
Ms Christian said she had told police during the interview that Mr Abbasi's detention breached the Human Rights Act and that his questioning was an abuse of process.
She added that her other client, Mr Mubanga - who was seen by one of her colleagues - was "very traumatised".
Ms Christian said relatives of the men had refused an offer to visit them because the police had insisted on being present at the meetings.
The men's lawyers have advised them not to answer any questions from the police.
Ms Christian left the building at the same time as Moazzam Begg's father, Azmat, who had been driven to London by police from his home in Birmingham.
Asked why Mr Begg had not seen his father, she said: "He's waited three years to see his father in dignified, free conditions and that is how he wants to see him."
Earlier, the lawyer for Mr Begg and Mr Belmar said the four men being held were victims of torture needing treatment and rehabilitation.
Clive Stafford Smith said they had been interrogated by MI5 in Cuba and should now be allowed to go free in Britain.
"I can guarantee you we will sue the American government," he added.
But Mr Stafford Smith said the men wanted a "simple apology" and would give any money won through the courts to charity.
Police say if there is no evidence against the four men, they will be released.
Mr Stafford Smith said that once freed, the men should not be subjected to surveillance in Britain.
"It's wrong that we take a British national and follow them around without them being convicted of any crime," he said.
The men landed in west London at about 1700 GMT on Tuesday
"These people have been tortured by the Americans and abused for three years and they need, not more interrogation, they need more rehabilitation."
Police have said they have a duty to investigate the men, who landed at RAF Northolt, west London, late on Tuesday afternoon.
They were immediately arrested under Section 41 of the Terrorism Act 2000 and were later visited by their lawyers.
Washington has claimed all four were "enemy combatants" who trained at camps run by al-Qaeda.
The Pentagon says they were freed after the UK government promised they would not be a threat to the national security of the US or any of its allies.