Several demonstrators were rushed to hospital on Monday after Greek riot police scuffled with protesting school guards trying to break through a police barricade in central Athens.
The unrest came as teachers launched strikes against the Government’s decision to cut jobs as part of its international financial bailout commitments.
Police used tear gas to break up the group of 100 school guards, who were attempting to enter the Administrative Reforms Ministry.
The incident in which about a dozen guards were injured occurred, radio reports said, as thousands of school teachers and other civil servants marched on Parliament in a separate rally. Some 10,000 demonstrators held a similar march in the northern port city of Thessaloniki.
High school and university teachers have begun rolling, five-day strikes; and social security staff have also joined the action.
The Government plans to suspend 25,000 public servants this year, and fire 15,000 by the end of 2014.
Union leaders say there are 16,000 fewer teachers, compared with last year, as a result of the changes.
Primary school teachers and lawyers said they would join a 48-hour walkout by civil servants starting on Wednesday. State hospital doctors are starting a three-day strike on Tuesday.
In July, some 2,500 teachers were placed in a scheme under which they will receive reduced wages until their transfer to another post, or be dismissed.
Greece is in a sixth year of recession, with record unemployment of 27.9 per cent.
Prime Minister Antonis Samaras has said the country is expected to return to growth at the end of 2014.
Representatives of the country’s international creditors — the European Commission, the European Central Bank and the International Monetary Fund — are due to return to Athens for an inspection visit later this month.