Holiday gone wrong

The two suspects work as purchasing officers at the hotel the students were staying at when they consumed the contaminated alcohol.

Three other service staff members from the bar and restaurant were taken in for questioning, but were later released.

Turkish media report that the hotel bought its spirits from a local company named Germiyan Pazarlama.

Investigators took 37 samples from products sold by the firm and found several contained high levels of methanol.

Detectives have so far been unable to find the firm's owner and fear he has fled.

Ineffective alcohol ban

The students involved in the poisoning were part of a school group from the Mortzfeld Vocational College in the northern German city of Luebeck.

Teachers had ordered them to stay away from alcohol, but seven students fell ill after drinking vodka on March 26.

Some of their beverages were apparently laced with methanol or industrial alcohol, which is toxic in large quantities.

The group only realised something was wrong when one of the students, a 21-year-old man, was found dead in his room.

Six other students were hospitalised. While four of them recovered, two teenagers who had fallen into a coma were flown back to Germany for specialist care.

After 12 days in a coma, doctors at the university clinic in Luebeck found the methanol had caused severe and irreversible brain damage and pronounced them clinically dead.

German authorities probe deaths

Medical authorities have classified the deaths "unnatural", which means autopsies have been ordered while German state prosecutors conduct a preliminary investigation into the circumstances of the incident.

Investigators are eager to answer two pressing questions.

One is whether the death of the first student could have been prevented. Germany's Der Spiegel magazine reports the young man lay in his bed for some 20 hours before anyone checked on him and realised he was dead.

The other question is where the alcohol really came from. Initial comments from the students involved suggested the victims may have bought the tainted spirits at a market outside the hotel grounds.

But the mother of one the youths who survived the poisoning says her son and his friends paid 25 euros for the drinks at the hotel bar.

"They definitely bought a sealed bottle of vodka, thinking they were drinking vodka and cola," she told German public broadcaster NDR.

What they were given was pure poison. It was definitely bought in the hotel, not, as some people say, from outside the hotel."

Turkey has a history of spurious liquors made by illegal home distilleries being sold in markets and restaurants.

In 2005, 22 people died, mainly in Istanbul, from a contaminated version of the Turkish national drink Raki, sparking a panic in bars throughout the country.

More recently, five people were found dead in similar circumstances in Bursa, just west of Istanbul.