Two men collapsed in western Germany on Tuesday after smoking cigarettes containing an unknown substance which they are believed to have purchased from the same vendor.

However, another person fell ill over the weekend because of this same substance.

The police said that paramedics had revived an unconscious 52-year-old man in the city of Duisburg who collapsed after smoking a cigarette laced with an unknown substance on Saturday evening.

According to the police, the man is no longer in critical condition.

In two similar incidents on Tuesday, a 43-year-old and a 45-year-old man collapsed after smoking contaminated and both men survived.

However, after questioning witnesses and obtaining a description of the potential cigarette vendor.

A suspect was detained on suspicion of violating the New Psychoactive Substances Act.

However, a search at the suspects home revealed no further evidence.

Investigators believe that the consumption of a cigarette containing an unknown substance caused severe cardiovascular complications that could have been fatal. (dpa/ NAN)