BERLIN (Reuters) - Residents of a refugee center in the German city of Duesseldorf set their shelter alight after a fight among Muslim refugees over Ramadan meals, a prosecutor said on Friday, in an incident that is likely to increase unease among anti-immigrant groups.

On Tuesday a fire ripped through the accommodation that was home to around 280 refugees on the site of Duesseldorf's trade fair. All residents were brought to safety but 24 suffered from smoke poisoning.

Ralf Herrenbrueck, senior public prosecutor in Duesseldorf, said there had been disputes among Muslims living in the home over how to celebrate Ramadan -- the Muslim holy month that revolves around daily fasts from dawn to sunset before meals during night hours -- before the blaze broke out.

"There are two groups -- one group wants to follow it strictly and so only eat when it's dark while the other group wants to eat at normal times -- for example because there are also pregnant women there," he said.

Herrenbrueck said the Red Cross, which is running the home, had decided to provide a basic lunch and only distribute warm food late in the evening, causing the group of Muslims that did not want to follow Ramadan strictly to complain since it started on June 6.

"They threatened that they would do something if this didn't change and when there was no warm food at lunchtime again on Tuesday, the arson happened," he said.

More than a million migrants arrived in Germany last year and while they were initially welcomed, the mood toward them has worsened as concerns about integration and security grow, boosting support for the far-right Alternative for Germany (AfD).

Five migrants were detained but three have since been released because they could not be directly linked to the fire, Herrenbrueck said.

Criminal police are investigating a 24-year-old Syrian, two Moroccans aged 18 and 26 and two Algerian men aged 16 and 26, police said in a statement.

Police said most of the men had been living in the accommodation under false names and having given false birth dates and countries of origin.

Herrenbrueck said a mattress was probably spread with alcohol and then set alight with a lighter.

(Reporting by Michelle Martin; Editing by Dominic Evans)