Two guests at a hotel in Thessaloniki who were found dead in their rooms in the space of 24 hours succumbed to carbon monoxide poisoning, possibly due to a faulty heating or air conditioning system, it was revealed yesterday.

The two unnamed men, aged 27 and 28, had been staying at the Nefeli Hotel in Thessaloniki’s Panorama district. The 27-year-old was found dead in his room on the fifth floor early on Thursday. A coroner said he had died from carbon monoxide poisoning. An expert was called to the hotel but could not find any leaks.

However, yesterday morning the other man, who was staying in a room on the fourth floor, was also found dead. The coroner found that as in the first case, there was a concentration of almost 90 percent carbon monoxide in the man’s blood. The hotel was evacuated after the second death and the manager has been arrested pending an investigation into exactly what caused the deaths.