India, Jan. 4 -- Air traffic was halted at airports across Greece after a radio frequency disruption on Sunday, according to the Greek state TV and the country's aviation authority.

The airspace over Greece suddenly emptied as flights were suspended nationwide.

Authorities said the cause of the disruption was under investigation. Greece's civil aviation authority said some overflights through the Athens Flight Information Region (FIR) were continuing, but restrictions had been imposed on airport operations as a safety measure, according to a Reuters report.

Flight-tracking data showed Greek airspace was largely empty. State broadcaster ERT reported that arrivals and departures at airports across Greece were suspended from 9:00 a.m. loc...