Athens - A brief strike by air-traffic controllers at Athens International Airport forced the cancellation or rescheduling of 35 flights Wednesday.

The debt-ridden state carrier, Olympic Airlines, said it would cancel 20 mostly domestic flights as a result of the three-hour stoppage, which starts at noon (0900 GMT).

Another 15 flights, including ones to London and Paris, are being rescheduled at Greek private carrier Aegean.

A nationwide strike has also been called by Greece's main public sector union ADEDY, forcing universities, tax offices, public schools, municipal offices and pharmacies to remain closed for the day.

State hospital employees also joined the strike, leaving hospitals to operate with a handful of emergency staff.

Unions are protesting the lack of pension security and intended privatizations, which they say will result in massive layoffs.

In September, the European Union approved the Greek government's plan to break up loss-making Olympic Airlines and fully privatize it by the end of 2009.

The government has announced 16 interested buyers.

The airline has accumulated losses of more than 2.5 billion euros (3.25 billion dollars).

The conservative government, under the leadership of Prime Minister Costas Karamanlis, has been rocked by recent scandals.

It said it will push forward with reforms and privatizations despite union opposition. It has promised to protect Greece's population from rising inflation. (dpa)