Upwards of 300,000 people took to the streets in Lisbon and other Portuguese cities on Saturday to protest job insecurity, responding to an initiative launched on the Facebook social network.

"There's No Freedom in Job Insecurity," marchers chanted in Lisbon's main artery.

"The Country Is on Its Knees," one banner read.

The Facebook appeal gathered 65,000 signatures, while some 200,000 people demonstrated in Lisbon and another 80,000 in Portugal's second city Porto, the LUSA news agency reported.

"Half of Portugal's active population is either unemployed or precarious, which shows that the situation is untenable," 27-year-old Joao Labrincha, who is unemployed and among the four organisers of the action, told AFP.

Portual, which had record unemployment last year at 10.8 percent, counts some 620,000 jobless, of whom nearly half are under 35 and more than 10 percent have a diploma.

Speculation has increased in recent days that Portugal will follow Greece and Ireland in being forced to accept an international bailout.

Finance Minister Fernando Teixeira dos Santos said Friday that Portugal would tighten austerity measures to ensure it meets its deficit reduction targets.