The number of refugees arriving in Greece on boats from Turkey has started to rise again, after being on a hiatus over the month, the International Organization for Migration said Friday, according to a report by Reuters. The report added that the increase in the numbers indicated that the “hermetic sealing” of the route to Europe seemed to be over.

“The arrivals in Greece which were down to literally zero this month are beginning to creep back up. In the last three days we had 150 people arriving each day... It does show that route might be picking back up,” Joel Millman, a spokesman for IOM told a news briefing in Geneva, according to Reuters, adding: “It could be the weather, it could be any number of things, it could be that smugglers are getting more creative.”

The latest report by IOM follows reports suggesting that about 500 people might have died after a ship sank over the weekend in the Aegean Sea. Only 41 people were said to have survived.

On Thursday, NATO Secretary General Jens Stoltenberg said that the number of refugees making their way across the Aegean Sea to Greece from Turkey had fallen significantly. NATO has been patrolling the Aegean Sea since February to curb the human trafficking.

He also praised Turkey for its coordination in controlling the refugee crisis along the lines of the deal Ankara signed with the European Union. “Turkey is at the forefront of a very volatile region. From terrorism and conflict in the Middle East and North Africa to Russia’s destabilizing military activities. Turkey is playing a crucial role in tackling human trafficking in the Aegean Sea,” Stoltenberg said at a press conference in Ankara.

The deal Turkey struck with the EU underlined that those arriving in Greece from the Turkish coast after March 20, will be deported back to Turkey. In exchange, the 28-member bloc promised to resettle one Syrian refugee from Turkey for each refugee that Turkey accepted from Greece. Ankara has also been given billions of euros in concessions along with a promise that the talks on Turkey’s accession to EU will be sped up.

About 2.7 million Syrian refugees are currently believed to be residing in Turkey.