Greece has announced its plans to extend its border fence with Turkey by 80 kilometers (50 miles) as pushbacks and Athen's harsh treatment of migrants trying to cross over to the country continue.

The existing 35-kilometer border fence is to be extended by 80 kilometers, Migration Minister Notis Mitarakis told the Skai radio station on Sunday. This would secure all regions that could otherwise be crossed on foot.

The announcement comes amid high tensions between Athens and Ankara.

The two NATO members are at loggerheads over natural gas, territories and many other issues.

Most recently, President Recep Tayyip Erdoğan declared that Greek Prime Minister Kyriakos Mitsotakis no longer exists to him, thus ruling out the possibility of talks.

Speaking in a televised address following a Cabinet meeting, Erdoğan said Mitsotakis spoke against Turkey and urged the U.S. Congress not to allow F-16 fighter jets to be sold to Ankara.

On the other side, Turkey has repeatedly condemned Greece's illegal practice of pushing back asylum-seekers, stating it violates humanitarian values and international law by endangering the lives of vulnerable migrants, including women and children.

Turkey's five Aegean provinces – Çanakkale, Balıkesir, Izmir, Muğla and Aydın – are prime spots for refugees seeking to leave Turkey for the European Union, with Greek islands within sight of the Turkish coast.

In recent years, hundreds of thousands have made short but perilous journeys across the Aegean to reach Northern and Western Europe in search of a better life.

Hundreds of people have died at sea as many boats carrying refugees often sink or capsize. The Turkish Coast Guard Command has rescued thousands of others.

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