Turkish President Tayyip Erdogan says his country's military and its Syrian rebel allies will advance 30-35km into Syrian territory in their offensive against Kurdish militia.
Speaking at a news conference in Istanbul, Erdogan says the Turkish-led forces have already seized control of the Syrian border town Ras al Ain, and have also besieged Tel Abyad.
He said two Turkish soldiers and 16 Turkey-backed Syrian rebels had been killed in the operation.
A Reuters witness said the Turkish army and its allies advanced into the centre of Tel Abyad, where the situation was calm and they were conducting search operations on Sunday.
Tel Abyad is one of the main focal points of the Turkish offensive that began on Wednesday against the Kurdish-led Syrian Democratic Forces.
The Syrian Observatory for Human Rights, a UK-based organisation that reports on the conflict, said Turkey and its allies were in almost complete control of the town.