The finger of blame which the Turkish government pointed at foreigners for orchestrating anti-government protests that rocked the country now appears to target foreign aid missions helping internally displaced Syrians.
Last week Turkish police raided offices of two humanitarian aid missions operating in war-torn Syria and deported four foreigners, witnesses said.
A Turkish official however denied the action was linked to the nationwide demonstrations that presented the Islamic-rooted Justice and Development Party (AKP) with its most serious challenge since coming to power more than a decade ago, saying that humanitarian aid missions in border regions must be registered.
A source familiar with the humanitarian efforts in Syria gave an account of two separate cases in the city of Antakya near the border with Syria where police detained one Spanish, one German and two British aid workers and deported them after hours of interrogation.
"You're aware of how difficult it is for humanitarians to operate in Syria, but we're also coming under increasing pressure from the Turkish state," the source told AFP on the phone.
"In one case last Wednesday an NGO staff member was forced off the road by unmarked police cars. Police caught him when he tried to run. His flat was searched. He was interrogated for hours and detained before being transferred to a counter-terrorism unit," the source added.
The following day, 30 police officers raided another NGO office, which was in the process of registration, according to the source.
"The charges shifted from evasion of police to drugs and to the suspicion of fomenting unrest," he said.
Several weeks of unrest, sparked by a local environment campaign to save a central Istanbul park from demolition, grew into nationwide protests against Prime Minister Recep Tayyip Erdogan's government, seen as increasingly authoritarian.
A defiant Erdogan has dismissed the protesters as "vandals" and "looters" and branded the turmoil a plot "hatched by traitors and their foreign accomplices."
In addition to the big cities like Istanbul and Ankara, protesters also took to the streets in Antakya -- which lies about 50 kilometres from the Syrian border.
The government's violent crackdown has left four people dead including a 22-year-old man who was fatally wounded during demos in Antakya last month.
The Turkish official, who requested anonymity, said that he was not aware of last week's incidents but insisted that whatever oreign aid organisations were experiencing in the country had nothing to do with the unrest.
According to a circular issued by the interior ministry, unregistered humanitarian aid missions should immediately stop working in Turkey, he told AFP.
"There are lots of NGOs. It's not clear who is working for whom. It's chaotic," he said. "We have launched a process to encourage them in order to legalise their presence in Turkey."
But the official admitted that the registration process was slow.
"Only five or six NGOs have received working permits so far, and many others have been waiting in line," he said, advising foreign aid missions to hire a lawyer to track the process.
Another source at a European NGO, which has an operation in Antakya for the supply of aid to Syria, said he was one of the foreigners detained for three days and deported at the weekend.
"Trumped up charges of spying, inciting Turkish people to join the Gezi park protests have been levelled at those NGOs," he said.
"It seems that the Turkish authorities both in Antakya and and Ankara may have connived to cause the maximum inconvenience to foreign organisations and their staff including all-night questioning and interrogation and attempting to get signed statements under duress."
He expressed concern that "humanitarian support for Syrian people has been put at risk" after Turkish authorities' tough action against the aid missions.
The United Nations said in May that the number of displaced Syrians has risen from around two million people to 4.25 million.
The figures -- combined with more than 1.4 million who have fled abroad -- mean that more than a quarter of Syria's pre-war population of 22.5 million have been forced to quit their homes since the conflict erupted in March 2011.
The overwhelming majority of the refugees have fled to neighbouring Lebanon, Turkey, Iraq and Jordan.
Aid workers are also being targeted by Syrian President Bashar al-Assad's regime and foreign aid missions use Turkey as a base to shuttle between Syria and Turkish border regions to supply Syrians with aid because of the dangerous situation on the ground.