Hundreds of people protested in central Athens Sunday against Greece's illegal pushbacks of migrants and refugees after 19 migrants froze to death last week as a result of the practices of Greek border units.

According to Greek police, around 700 people marched from Omonia Square at the center of Athens to Syntagma Square in front of the Greek parliament.

The demonstrators carried a life raft resembling the ones allegedly used by Greek authorities to push back asylum-seekers from Greek territory, an Agence France-Presse (AFP) photographer said.

Protesters, who gathered after a call by leftist and anti-racist groups, shouted slogans against "the assassination of migrants at the border" and held banners reading "Stop pushbacks and border violence."

In Syntagma Square they observed a minute of silence for the migrants who lost their lives.

Decomposed bodies of irregular migrants found in Aegean

Meanwhile, Greek coast guard units discovered more bodies of irregular migrants six weeks after a boat carrying them capsized as they were trying to reach Europe.

The bodies of two men and a woman were badly decomposed, the coast guard said on Monday. The authorities assume that they were migrants who had not been found after their boats capsized at the end of December.

Several bodies have washed up on the Aegean islands since the accident.

Some 30 people died off the islands of Folegandros, Paros and Crete after their vessels capsized. Dozens of people are still missing.

The migrants were trying to get to Calabria in Italy and had traveled from Turkey, crossing the Aegean Sea, a journey made by many to avoid having their valuable possessions and clothes stolen, assaulted and pushed back by the Greek authorities or a potentially long stay in one of the refugee camps on the Greek islands if they can make it through.

However, the long sea journeys often result in boats experiencing engine failure, leaving migrants to drift on the rough sea exposed to the elements. Furthermore, many wind up in boats that are damaged or leak.

It is not possible to estimate how many people died trying to make the journey, claimed the Greek coast guard.

Last week, Turkey said it found 19 frozen bodies close to the Greek border, accusing Athens of allowing the migrants to die in the winter cold after stripping them of their clothes and forcing them back across the border. Greece has strongly rejected the accusation.

Human rights groups believe such actions, reported by migrants in different parts of the world, are designed to discourage fleeing people from trying to enter a particular country and to look for a different route.

President Recep Tayyip Erdoğan vowed last week to expose Greece's alleged illegal pushbacks of migrants at every opportunity.

The incident also received harsh criticism from Turkey's defense and foreign ministries. Greece must immediately end its inhumane practices on land borders and at sea, the Defense Ministry said on Friday.

"The images of migrants, whose clothes, shoes, everything was taken on their journey toward holding on to life and who lost their lives as a result of this inhumane treatment, has upset everyone," the ministry said on Twitter.

"These practices must henceforth draw the attention of the EU," the Defense Ministry stressed while the Foreign Ministry in a similar statement said that "The EU keeps silent in the face of Greece’s cruel practices against irregular migrants and turns a deaf ear to our calls. We call on the international community to investigate Greece’s actions in violation of human rights and not to remain indifferent to these despicable acts."

Turkey's interior minister said initially that 12 migrants had died after allegedly being forced back into Turkey. He said they were found near the border, "without shoes and stripped of their clothes." One of the migrants was found alive but later died in hospital. There was no information about the migrants' nationalities.

A statement from the border province of Edirne governor's office said seven more bodies were found on Thursday. Anadolu Agency (AA) reported that gendarmerie forces were searching the area with the help of drones and that medical teams were on standby.

Recent years have seen multiple reports of Greek forces illegally pushing back boats of asylum-seekers, endangering the passengers in the process.

Turkey is a major crossing point for migrants from the Middle East, Asia and Africa seeking a better life in European Union countries.

Most try to cross into Greece – a key gateway to the EU for people fleeing war or poverty – by either crossing the northeastern land border or cramming into boats headed for the eastern Aegean Sea islands.

Speaking to reporters before departing for a visit to Ukraine, Erdoğan said he would bring up the issue of Greece's ill-treatment of migrants during every meeting he holds with world leaders. He also accused the European Union of not speaking out against illegal pushbacks and the EU’s border and coast guard agency, Frontex, of allegedly "supporting" Greece.

Greece’s Migration Minister Notis Mitarachi on Wednesday described the deaths as a "tragedy" but strongly denied the claim that Greek forces had pushed back the migrants, insisting that the migrants never made it to the border.

Pushbacks are considered contrary to international refugee protection agreements, which dictate that people should not be expelled or returned to a country where their life and safety might be in danger due to their race, religion, nationality or membership in a social or political group.