The hulking Greek coastguard officer gazed intently as another group of migrants, the fifth of the day, boarded a minibus after landing on a beach on the island of Lesbos.

"We're taking it day by day," he sighed, amid talk of a new refugee crisis, four years after nearly one million asylum seekers arrived on Europe's doorstep, sparking EU-wide panic.

Arrivals by sea from Turkey to Greece increased to 10,258 in September - the highest monthly total since 2016
Arrivals by sea from Turkey to Greece increased to 10,258 in September - the highest monthly total since 2016 AFP / ANGELOS TZORTZINIS

The UN refugee agency (UNHCR) announced on Tuesday that arrivals by sea from Turkey to Greece, mostly Afghan and Syrian families, increased to 10,258 in September.

It said this was the highest monthly total since 2016, when the EU reached an accord with Turkey to stem the flow of arrivals.

The surge has left an already overburdened Greek asylum camp network -- which the UN terms "inhumane" -- struggling to cope.

The surge in arrivals has left an already overburdened Greek asylum camp network struggling to cope
The surge in arrivals has left an already overburdened Greek asylum camp network struggling to cope AFP / ANGELOS TZORTZINIS

"In the last couple of months (there has been) an incredible contrast... a huge increase, quite sudden," said Patrick Foley, emergency response coordinator for the Swedish NGO Lighthouse Relief that operates in the north of Lesbos, where most asylum seekers land.

"Each month is typically more than the month of the previous year".

Refugees and migrants trapped in the Moria camp on Lesbos are increasingly angry at conditions there
Refugees and migrants trapped in the Moria camp on Lesbos are increasingly angry at conditions there AFP / ANGELOS TZORTZINIS

In May, the NGO was helping around 70 people land safely on Lesbos beaches and giving them temporary shelter.

'Unpredictable'

This climbed to over 2,800 in September after similar numbers in August, Foley said.

"It's really unpredictable. It could literally overnight just go back to normal again and it could be a short trend, or it could be a continued increase," he said.

Greece plans to return to Turkey 10,000 migrants who fail asylum requirements by the end of 2020
Greece plans to return to Turkey 10,000 migrants who fail asylum requirements by the end of 2020 AFP / ANGELOS TZORTZINIS

Greek islands opposite Turkey now host more than 26,000 asylum seekers in camps built to handle just a fraction of these numbers.

In addition to poor hygiene and frequent outbreaks of violence, many of the residents sleep in tents and complain of having to queue for hours to obtain food, take a shower or use a toilet.

In addition to poor hygiene and frequent outbreaks of violence, many of the residents sleep in tents and complain of having to queue for hours to obtain food, take a shower or use a toilet
In addition to poor hygiene and frequent outbreaks of violence, many of the residents sleep in tents and complain of having to queue for hours to obtain food, take a shower or use a toilet AFP / ANGELOS TZORTZINIS

"Keeping people on the islands in these inadequate and insecure conditions is inhumane and must come to an end," the UNHCR said Tuesday.

On Sunday, a fire killed a woman in the Lesbos camp of Moria, sparking brief rioting between asylum-seekers and police.

"We urge the Greek authorities to fast-track plans to transfer over 5,000 asylum seekers already authorised to continue their asylum procedure on the mainland," the UNHCR said in a statement.

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"In parallel, new accommodation places must be provided to prevent pressure from the islands spilling over into mainland Greece, where most sites are operating at capacity."

EU Migration Commissioner Dimitris Avramopoulos is set to visit Greece and Turkey this week with the foreign ministers of Germany and France to discuss the situation.

Greece's minister for migration also travels to Ankara on Wednesday for talks with the Turkish interior minister.

Many in Greece say Turkey is not doing enough to keep its end of the bargain in thwarting attempts to cross the Aegean Sea, which result in hundreds of deaths annually.

But according to Foley, it appears that fear of arrest in Turkey spurs many migrants -- Afghans in particular -- to head to Greece as fast as possible.

"A lot of people coming from Afghanistan (spend just) a couple of weeks in Turkey and then make the crossing. A lot of people are becoming afraid of deportation from Turkey," he told AFP.

Foley notes that migrants and refugees are "somewhat" aware of the grim conditions that await them in Greek camps even before attempting the perilous crossing.

Tougher stance

"(But they) believe things can't get worse than the situation that they're already in."

The new conservative Greek government, elected in July, has vowed to take a tougher stance on migration.

It plans to return to Turkey 10,000 migrants who fail asylum requirements by the end of 2020.

There are also promises to relocate hundreds of refugees to camps on the Greek mainland.

But in four and a half years under the previous left-wing Greek government, Turkey took back fewer than 2,000 people.

And at the current rate of arrivals, any de-escalation in camp numbers will be rapidly neutralised by new arrivals.

Two more boats arrived on Wednesday morning, raising the combined total to around 300, Foley said.