BUDAPEST, HUNGARY - TALKS between striking unions and Budapest Airport broke down on Sunday, unions said, causing more delays and flight cancellations at Hungary's biggest international airport.

Two unions at Budapest Airport, a unit of Germany's Hochtief, started an indefinite strike on Wednesday over demands for improved labour conditions, a new collective agreement and a halt to layoffs.

Talks to resolve the standoff collapsed on Sunday. In a statement the unions said they saw no chance for a resolution with the airport operator, which failed to adequately address either of their demands.

They later said other unions were considering a solidarity strike next week, threatening to bring the airport to a standstill.

Budapest Airport said on its website it had agreed to continue talks with unions at 1000 GMT (6pm Singapore time) on Monday.

Hungarian airline Malev, which cancelled 10 flights on Sunday, said it would scrap another 12 scheduled for Monday.

Low-cost carriers EasyJet and Wizz Air cancelled two Sunday flights scheduled for Berlin and Brussels, respectively.

The airport said it expected an improved service on Monday but added further delays were possible and advised passengers to arrive three hours before departure.

News agency MTI reported earlier on Sunday Wizz Air was considering legal action against Budapest Airport for the damages it had incurred during the strike.

Separately, railway workers' union VDSZSZ extended a strike launched in eastern Hungary on Sunday to all lines after 1700 GMT to demand higher wages and a one-off bonus from the sale of state railway firm MAV's freight unit.