He went on to stay in camps in Potsdam and Eisenhüttenstadt, Germany, using 10 different identities.
In some places the journalist had his fingerprints taken - but the identities were never matched up.
He said: “The system does not work and I know employees from the Federal Office for Migration and Refugees or from the Federal Criminal Police Office, who tell me that it has not worked so far.
“In my case, no-one noticed any of my double registrations, although I had my fingerprints registered in some cases.”
Mr ul-Haq stayed in the infamous Tempelhof Airport hangar where sex assault among refugees have been rife and conditions widely criticised.
He said: “This is the largest refugee home in Germany, and there is an incredible amount of problems.
“In my opinion, nobody can be expected to live there. Earlier on, the lights were switched on at night, so you could hardly sleep.
“At least this is different now. Then the toilets. They stink, and I find that they can hardly be used. Many people don't like the food, and there was also sexual abuse among the refugees.
“In addition, many people from different countries live together, which leads to conflicts and struggles.
“The worst thing is that people have nothing to do. They hang around all day without any occupation. Some of them get into mischief.
“Refugee camps are a breeding ground for salafists and terrorists. Sometimes it is said that Germany was importing terrorists. When in fact we breed them ourselves.
“There are appeals from Salafists. They shave off their beards and offer help to relief organisations.
“I noticed that myself. Then they talk to the refugees, invite them to dinner, and take them to a mosque marked by Salafists. In Berlin, for example, this is the Al-Nur-Mosque in Neukölln. This is how refugees fall in the wrong hands.
The now German citizen, Mr ul-Haq, was shown pictures of people as they posed with weapons in Syria.
One, he claims, told him of how he fought for al-Nusra in Syria.