Greek authorities on a number of Aegean islands have called for emergency measures to curtail a growing flow of refugees from Turkey, which Athens attributes to the impact of the attempted coup in that country.

Since the failed 15 July putsch, the number of Europe-bound migrants willing to make the perilous journey across the Aegean has increased noticeably, with the Greek government announcing that as of yesterday some 9,420 men, women and children had been registered on Lesbos and other islands.

As the annual holiday exodus to the Mediterranean got under way, the regional governor of the north Aegean, Christiana Kalogirou, sounded the alarm, saying it was imperative that immediate steps were taken to stymie the “constant and apparently increasing flow”. On Lesbos one rescue worker said scenes had become eerily reminiscent of the days before Europe cut a deal with Turkey in March to curb mass arrivals.

Highlighting the anxiety, the EU president Jean-Claude Juncker said in the wake of the coup that he feared the accord was at breaking point. “The risk is big. The success so far of the pact is fragile,” he told the Austrian daily Kurier on Friday. “President Erdoğan has already hinted several times that he wants to scrap it.”

There are similar concerns in Athens where officials voiced worries that Turkish monitors overseeing the deal in Greece had been abruptly pulled out after the failed coup with little sign of them being replaced.

Tensions between the two long-standing regional rivals have been fuelled by the case of the eight Turkish officers who fled across the border in the final throes of the attempted takeover. The soldiers, who landed in a Black Hawk helicopter, were given three weeks by a tribunal on Thursday to prepare asylum applications as Ankara stepped up pressure for their immediate return to Turkey.

In a sign of the tensions their presence has unleashed, a Greek anarchist group attacked the residence of the Turkish ambassador Kerim Uras, daubing the building with pots of black and red paint on the day they appeared before the tribunal.

The envoy has scorned the idea that leftwing anarchists should elect to act in support of a fascist coup in which blood had been shed and crimes enacted. “These were people who were trying to demolish democracy in Turkey. They were killing citizens and shelling institutions with laser-guided bombs. They weren’t upholding human rights,” he said.

But Uras added that the eight military personnel, who transmitted a mayday signal as they flew into the frontier town of Alexandroupolis, should never have been given shelter in Greece at all. The officers – two colonels, four captains and two sergeants – are the first to seek refuge in the country in modern history.

“It wasn’t a good idea to let them in in the first place,” said Uras. “They should have been sent back very fast. Now they are clearly exploiting the asylum procedure.”

Greek prime minister Alexis Tsipras’s leftist government, confronting the dilemma of antagonising Turkey at a delicate stage in peace talks on Cyprus, has attempted to walk the middle ground: pledging the men will be given a fair hearing under European law but that Turkey has a strong argument for their extradition.

Much, however, will depend on whether Erdoğan acts on his pledge to reinstate the death penalty in Turkey.