Greece's prime minister is criticizing Turkey for preventing a NATO force in the Aegean Sea from expanding its activities further south as part of its deployment to help tackle the refugee crisis.

NATO has deployed ships in the northern Aegean to help combat migrant smugglers taking people from Turkey to Greek islands, but it has not deployed in the southern Aegean area. Greece says this is because Turkey objects, considering it to be a demilitarized area.

Alexis Tsipras also says Turkey has increased airspace violations in the Aegean with its fighter jets, and that Greece "will not accept or tolerate any actions which violate or dispute our sovereign rights."

Tsipas was speaking Friday after meeting with NATO Secretary General Jens Stoltenberg.