LISBON - Tens of thousands of public school teachers and other staff marched in Lisbon on Saturday to demand higher wages and better working conditions, putting further pressure on the Portuguese government as it grapples with a cost of living crisis.

Shouting slogans like "for the banks there are millions, for us there are only pennies," about 80,000 protesters filled the Portuguese capital, police said.

A year after Socialist Prime Minister Antonio Costa won a majority in parliament, he is facing a slump in popularity and street protests not just by teachers but by other professionals such as doctors.

The Union of All Education Professionals (STOP) is demanding that the government increases the wages of teachers and school workers by at least 120 euros ($130) a month and speeds up career progression.

The government has not made a counter-proposal specifically for teachers but has said it will increase the monthly salaries of all civil servants who earn up to about 2,600 euros by 52 euros.

Teachers complain that, because of career freezes in the past, they are the lowest-paid senior civil servants, which means their financial situation has worsened after a recent spike in inflation to a 30-year high.

Teachers on the lowest pay scale are paid around 1,100 euros per month and even those in the top band typically earn less than 2,000 euros monthly.

"For years, they (politicians) kept us silent. We need better conditions in terms of salary, it's unacceptable that we don't have progression in our careers," said Isabel Pessoa, 47, a science and biology teacher.

Teachers and other education staff across the country have been taking strike action since early December, closing many schools and leaving students unable to attend classes. The strikes have been organised on an area-by-area basis with successive days of action in each of Portugal's 18 districts.

The government has criticized STOP for the way it has organised the strikes because, it says, it does not have a pre-set timetable and teachers and staff only refuse to work certain hours on a specific day but are still able to close schools.

($1 = 0.9202 euros)

(Reporting by Sergio Goncalves and Miguel Pereira; Additional reporting by Pedro Nunes and Graham Keeley; Editing by David Holmes)