Two people have been arrested on suspicion of arson at Dusseldorf Messe in western Germany. Hall 18 of the convention centre site, housing asylum seekers, was destroyed in the fire.
Thirty migrants were treated for smoke inhalation and more than 200 were evacuated from the hall after the blaze on 7 June.
Damage at the hall, which is close to the airport, has been estimated at 10m euros (US$11m).
Initial reports speculated that the blaze was sparked out of a conflict between Arab groups on one side and a minority of Afghans and Iranians employed at the centre.
Dusseldorf’s Express newspaper said the situation stemmed from anger on the part of some of the Arabs over their Ramadan breakfast.
Three weeks earlier there were reports of a smaller fire at the centre as a migrant set fire to his mattress in protest against the accommodation.
One of the 70 fire-fighters who turned out to tackle the blaze was hospitalised due to heat exhaustion.
The BBC reported two North African men had been arrested and charged with arson.
