Rome - Schools in Italy remained closed Thursday as teachers went on strike over controversial education reforms adopted by Prime Minister Silvio Berlusconi's government.

Thousands of students, parents and teachers joined protest marches organized by the country's major labour unions in several cities.

Leaders of the centre-left opposition which is supporting the strike also joined the protest marches.

Around mid-morning, a crowd began moving from Rome's Piazza Repubblica square towards the central Piazza del Popolo square where the protest was set to culminate with speeches by leaders of the main CGIL, CISL and UIl unions.

Parliament, where Berlusconi's conservatives hold a comfortable majority, gave final approval to the reforms on Wednesday.

Education Minister Mariastella Gelmini says the reforms are aimed at cutting unnecessary costs and to improve pupils' discipline by introducing marks awarded for conduct.

The minister has refused back down despite country-wide protests which began late last week, including student sit-ins outside parliament buildings.

The leader of the main opposition Democratic Party, Walter Veltroni, has accused the government of "arrogance" and has announced moves to have a referendum on the issue.

Berlusconi has criticized the protests saying that the students are allowing themselves to be used as "tools in the hands of leftists."

On Wednesday, several people were injured in Rome when some of the protestors were attacked by far-right students wielding chains and poles, news reports said.

Opponents of the government plan include unions who say that the planned re-introduction of having only one teacher per primary school class, has raised concerns that tens of thousands of teachers may lose their jobs.

Many parents fear a drop in education standards because they believe a single teacher will not be able to adequately cover subjects as diverse as languages and arithmetic.

Also, time spent at school would be slashed from 29 to 31 hours a week currently, to 24. This, critics say, places a further burden on working parents as they will have to arrange supervision for their children during longer hours spent outside school.

The protests which began late last week at schools, spilled over to the country's public universities which are facing budget cuts including the proposed scrapping of scores of courses and in some cases the closure of faculties.

The students have been joined by professors and lecturers who in a sign of protest against the government proposals have started delivering lectures in streets and squares, including outside tourists landmarks such as the Coliseum in Rome or Saint Mark's Square in Venice. (dpa)