Thousands of Portuguese police officers, paramilitary police and other security officers took to the streets of the capital to protest the government's latest austerity measures.
Police in plain clothes massed outside parliament, where they broke through a security cordon to briefly occupy the steps leading up to the building.
During an earlier march, they had called for the government to resign, carrying a banner that read "For professional dignity and people's security."
Unions said the rally was the biggest ever organised by the country's police, and warned that budget cuts planned for next year would "destabilise the work of the police" and "deteriorate public security."
Media reports estimated the number of demonstrators at between 8,000 and 10,000.
"I've been with the police for eight years and never got promoted or a pay rise, even though I have a family now and more responsibilities," complained protester Manuel Ribas, 32.
"Next year, they will take another 100 euros [$135] out of my gross salary, which will leave me with 900 euros a month, just as if I had just left the police academy."
A 50-year-old paramilitary police officer from the northern Aveiro region, who would not give his name, said he was "absolutely disappointed" as the new cuts were "still more discouraging."
Portuguese border police began four days of rolling strikes on Thursday.
Portugal has enacted and continues to ramp up radical measures to reduce its public deficit and increase the efficiency of its economy to receive rescue loans of 78 billion euros.
The bailout programme lasts for three years with the intention that next year, Portugal will have rebuilt sufficient credibility to be able to finance its deficit and debt on the sovereign bond market in the normal way.
The rescue became necessary when investors took fright at the state of public finances in Portugal, at the same time as crises in Greece and Ireland, and became reluctant to lend to the government, with the consequence that market borrowing rates for the country rose to unsustainable levels.