Turkey-based smugglers have begun to re-advertise trips between Turkey and Italy, in the first hint of a shift in migration patterns since the EU agreed a deal to deport any refugees landing in Greece.

In an advert on Facebook, smugglers claimed that the first boat to Italy would leave this weekend from the port of Mersin. They offered places for $4,000 (£2,780) per person, four times the cost of a journey from Turkey to Greece.

“The trip is on Saturday, from Mersin to Italy, on a merchant ship 110 metres long, equipped with food, water, life jackets and medicine,” the post read, accompanied by photographs of a cargo ship.

Reacting to the ad, some refugees raised the possibility of the scheme being a scam, since scores of would-be migrants were tricked in 2014 and 2015 by people posing as organisers of similar trips.

In response, the ad’s author claimed that passengers’ money would be held by a third party trusted by both the smugglers and passengers, meaning that the former stood to gain little if their clients failed to arrive in Italy.

Whatever the truth, the development nevertheless indicates increased demand for alternative routes to Europe now that it has become harder to leave Turkey for Greece.

Over the past year more than one million refugees have reached the EU by crossing the sea between the Greek and Turkish coasts. But this tactic has all but stopped in the past two weeks after the EU agreed a deal that in theory could mean almost all those arriving at the Greek islands eventually being deported back to Turkey. Turkey’s prime minister Ahmet Davutoğlu said on Thursday that the deal will go into effect as scheduled on Monday.

Contacted by the Guardian, the smuggler who posted the advert claimed it was the first time he had organised a journey to Italy in months. He refused to confirm where in Italy the boat would land.

Alarmed by this lack of detail about the voyage, some travellers worried that the trip could be bogus. “Are we back in the time of fraud?” one person commented under the smuggler’s ad.

If revived, the Turkey-Italy trips would mark the rejuvenation of a tactic that had faded in the past 12 months.

During the winter of 2014-15, about a dozen co-opted cargo boats – known as “ghost ships”because of the crews’ tactic of abandoning them then sending them on autopilot towards ports – arrived in Italian waters from Turkey.

But the practice almost ceased in early 2015 after a crackdown by the Turkish authorities in Mersin and the emergence of the passage to Greece.

Responding to claims of a revival in the route, a spokesman for the International Organization of Migration, which monitors migration patterns in the Mediterranean, said the group had not detected any recent arrivals in Italy from Turkey.

“Departures from Turkey are a possibility, but I remember that in January 2015 the so-called ghost ships were blocked at sea by Turkish authorities,” the spokesman said. “It is not going to be easy, even now.”

Migrant arrivals to Italy since the start of 2016 are higher than the equivalent periods in both 2015 and 2014, when record numbers landed in southern Italy.

About 18,200 people have already arrived since 1 January, compared with 10,000 over the same periods in 2014 and 2015, according to figures released by the Italian government.

There is not yet a correlation between the rise in these arrivals and the crackdown on crossings between Greece and Turkey.

The majority of those arriving in Italy are not Syrians, according to statistics compiled by the Italian government and provided by the UN human rights committee. They are primarily people fleeing Gambia, Nigeria and Senegal (there have also been 1,500 Egyptian minors).

According to the Italian newspaper La Repubblica, Italian officials are predicting that the number of people landing in Italy could reach 270,000 this year – significantly higher than the 150,000 in 2015, and the 170,000 in 2014.

Additional reporting by Eiad Abdullatif