Greek police have stepped up efforts to catch illegal immigrants in recent months, launching a new operation to check the papers of people who look foreign. But tourists have also been picked up in the sweeps - and at least two have been badly beaten.
When Korean backpacker Hyun Young Jung was stopped by a tall scruffy looking man speaking Greek on the street in central Athens he thought it might be some kind of scam, so he dismissed the man politely and continued on his way.
A few moments later he was stopped again, this time by a man in uniform who asked for his documents. But as a hardened traveller he was cautious.
Greece was the 16th stop in his two-year-long round-the-world trip and he'd often been warned about people dressing in fake uniforms to extract money from backpackers, so while he handed over his passport he also asked the man to show him his police ID.
Instead, Jung says, he received a punch in the face.
Within seconds, the uniformed man and his plainclothes partner - the man who had first approached Jung - had him down on the ground and were kicking him, according to the Korean.
It was only when he was handcuffed and dragged 500m (500 yards) up the road to the nearest police station that he realised he was actually under arrest.
Jung says that outside the station the uniformed officer, without any kind of warning, turned on him again, hitting him in the face.
Inside the police station, Jung says he was attacked a third time in the stairwell where there were no people or cameras.
"I can understand them asking me for ID and I even understand that there may have been a case to justify them hitting me in the first instance. But why did they continue beating me after I was handcuffed?" he asks.
Jung was held with a number of migrants from Africa and Asia who had also been rounded up as part of the police's anti-immigration operation Xenios Zeus - named, strangely, after the ancient Greek god of hospitality.(lol)
When Jung was released from police custody without charge just a few hours after being detained, he says one officer shouted after him, "Hey Korean, go home!"
It is thought that up to 95% of undocumented migrants entering the European Union arrive via Greece, and because border controls make it hard to continue into the rest of Europe many end up stuck in the country.
Lt Col Christos Manouras of the Hellenic police force says operation Xenios Zeus, launched last August, has slowed down the flow of illegal immigrants. Anyone who looks foreign, or who has aroused suspicion, may be stopped, he says.
"If someone is stopped by the police and they do not have a valid means of identification we will accompany them to the station until their nationality can be determined," he explains.
"I think that is normal and I would expect Greeks to be subjected to the same treatment abroad."
But while more than 60,000 people have been detained on the streets of Athens since it was launched in August 2012, there have been fewer than 4,200 arrests.
And some visitors to Greece have been detained despite having shown police their passports.
Last summer, a Nigerian-born American, Christian Ukwuorji, visited Greece on a family holiday with his wife and three children.
When police stopped him in central Athens he showed them his US passport, but they handcuffed him anyway and took him to the central police station.
They gave no reason for holding him, but after a few hours in custody Ukwuorji says he was so badly beaten that he passed out. He woke up in hospital.
"I went there to spend my money but they stopped me just because of my colour," he says. "They are racist."
Christian Ukwuorji, who also lodged an official complaint against the police with the help of the American Embassy, has now been waiting for more than six months for an outcome.
"The police there are very corrupt and nothing will be done about it," he says. "I have learned that this is how Greece is."
Tourism is a major source of revenue in Greece, especially important at a time when many other businesses are going bust. Anything that deterred visitors in large numbers would be a disaster for the economy.
It is not only tourists who have been affected.
In May last year a visiting academic from India, Dr Shailendra Kumar Rai was arrested outside the Athens University of Economics and Business, where he was working as a visiting lecturer.
He had popped out for lunch, and forgotten to take his passport with him.
"The police thought I was Pakistani and since they didn't speak English they couldn't understand me when I tried to explain that I am from India," he says.
When passing students saw their lecturer being held by police and lined up against a wall with a group of immigrants they were horrified and rushed inside to tell his colleagues.
Despite protests from university staff who insisted they could vouch for him, the police handcuffed him and marched him down to the police station.
"I understand why the police need to ask for identity documents, they are just doing their job. But I think they are too aggressive - in my country only criminals are handcuffed."
Rai says he experienced no racial prejudice during his time in Greece, and does not accuse the police who arrested him of racism.
But in a report for 2012, the Racist Violence Recording Network, a group consisting of 23 NGOs and the UN High Commissioner for Refugees, called on the Greek government to "explicitly prevent police officers from racially motivated violent practices" referring to 15 incidents where "illegal acts" had taken place.