The Immigration Minister told a failed asylum seeker live on television to go home - as he had no right to be in the UK.
During the confrontation on a BBC show, Mr Harper said that the Government and the courts did not believe Mr Amin's claims and the British taxpayer should not support him.
Mr Harper, who signed off the controversial "Go Home" advertising vans which toured London this summer, came face to face with Mr Amin on BBC1's Sunday Politics West show.
He told him: "Let's be very clear Mr Amin has had the chance to claim asylum and his case has been looked at very carefully by the government and we didn't find it credible.
"We have a fair system where he is able to go through a legal process. The judge didn't find his claim credible. In fact he said parts of his claim were 'not credible' and 'ridiculous'.
"I'm afraid he has no right to be in the United Kingdom and he should leave."
Mr Amin, who lives in Bristol, told the minister: "I am not an illegal person, I am an asylum seeker and I am a human being like you.
"My life in my country is in danger that's why I decided to left my family and everything.
"I came here and I claim as an asylum seeker and find safe place. You didn't believe me and I know my story is true and your system not believe me."
Mr Amin said he had been turned down for asylum five times by the British authorities, since arriving in the UK.
"Nearly six years I am living in England and I can't return to my home because my life is in danger there," he said.
"I am going to continue to get my right to get a safe place."
Mr Amin added: "I can't go back to my country as my life still in danger there and there is a risk for me, that's why I come here.
"My friends here are helping me. I want to ask you can you live on £5 a day?"
Mr Harper, who is the Conservative MP for the Forest of Dean in Gloucestershire, replied: "With the greatest respect when you were here claiming asylum taxpayers supported you.
"You have no right to be in the United Kingdom and you should return home."
Mr Amin said that he could not return to Iraq, as his life was in danger.
"There are a lot of people like me living in the park, there is no room for them," he said.
"They are living in the park, in the bus shelter. Maybe I am lucky, I have a friend and they are helping me.
"They are giving me a place to live and they are giving me clothes and food."
During the 10-minute discussion on the show, Mr Harper said: "Hardworking families will be sat there incredible that someone has had the chance to go through a system, have had a decision, they have appealed it to a judge and they have been found not to have the need for our protection.
"They would think it is incredible that the taxpayer should continue supporting them to stay in this country when they have no right to be here.
"It doesn't give everyone in the world the right to come to the United Kingdom.
"We protect people and we are very generous at protecting people genuinely fleeing persecution and I think if people abuse our system it will damage the British public's tolerance for people genuinely fleeing persecution."
He added: "Britain is a very welcoming country for people who have a claim to be here but we do expect people to play by the rules.
"For people, who are claiming asylum when their claim is being processed, we want to be very welcoming but when someone's not had their claim granted and they've had their chance to appeal then they should leave the country.
"We have been very clear that if someone needs urgent healthcare they will get it. If someone shouldn't be here, they shouldn't be here.
"The health service is a national health service and not an international health service."