Greek flights will be grounded for four hours Thursday when air traffic controllers walk off the job to join a 24 hour public sector strike against salary cuts and pension reforms.

The nationwide strike was called by public sector unions representing more than half a million workers.

"Flights to and from Greek airports will be halted between 1000 and 1400 local time (0700-1100 GMT)," Panagiotis Hatzakis, a senior member of the air traffic controllers' union, said on Wednesday.

Only emergency flights would land and take off, he said.

Aegean Airlines said it would cancel 44 domestic flights and one flight to/from Bucharest and reschedule 37 others.

The strike, which is expected to shut down ministries and public services, is the latest in a series of protests since the police shooting of a teenager in December sparked the country's worst riots in decades.

Greece is hit sharply by the economic downturn and may face a recession in 2009 after years of sustained growth.