Police and students clashed outside the Greek parliament Tuesday despite an appeal for calm by the president ahead of the funeral for a 15-year-old boy whose killing by police set off nationwide riots.
The troubles entered a fourth day as Prime Minister Costas Karamanlis appealed for national unity to end the violence and the family of 15-year-old Alexis Grigoropoulos prepared to hold his funeral.
Authorities closed off many Athens streets after a third night of rampaging violence by youths who looted banks and stores. Police, who made 87 arrests, said some protesters staged attacks with swords and slingshots stolen from a weapons shop.
Twelve more police were injured in Monday's clashes and at least 10 people were hospitalised with respiratory problems from clouds of tear gas that blanketed central Athens.
The latest unrest on Tuesday flared outside the parliament where a molotov cocktail was thrown at riot police during a protest by students.
Earlier tear gas battles had been staged at the Athens Polytechnic which along with the nearby Athens Law School has been occupied by students protesting at the killing.
Streets around the universities were closed. Both colleges are in the Exarchia district where Grigoropoulos was fatally shot by police on Saturday, setting off the worst unrest to hit Greece in decades.
Thousands of teachers and students took to the streets of the capital to demand justice.
Around 2,000 protesters, led by the OLME teachers' union, marched on the Greek parliament carrying a large banner reading "Assassins, the government is the culprit".
Burnt out rubbish bins, glass and paving slabs torn off sidewalks littered the streets from the third night of troubles on Monday when emergency services said fires were put out at 49 office buildings, 47 shops, 14 banks, 20 cars and three ministries.
The northern city of Salonika also saw major unrest. At least 70 stores and seven banks were set ablaze, according to the ANA news agency. Several thousand students staged a protest march there on Tuesday.
The funeral of Grigoropoulos was to be held at the southern Athens suburb of Palio Faliro at 1300 GMT.
He was allegedly among a group of youths that had thrown stones at a squad car in a district of Athens that is known as a radical stronghold. The policeman who fired the shots and his partner have been arrested.
Universities and schools have been closed, students planned their own protest rally on Tuesday and unions have said that a general strike, which was called before the killing, will go ahead.
The mass unrest has piled pressure on the conservative prime minister who vowed on Monday to end the troubles.
Karamanlis called a crisis cabinet meeting on Monday night and held new meetings with President Karolos Papoulias and leaders of allied and opposition political parties on Tuesday.
"We will tolerate no leniency in the attribution of responsibility," the prime minister said after talks with the president.
"In these critical hours, the political world must unanimously condemn and isolate the perpetrators of this violence," Karamanlis said.
The president appealed for calm, calling on Greeks to "honour Alexis' memory peacefully."
"This is a day of mourning for us all...but there must be respect for institutions and laws," Papoulias said in a statement.
But the government, already in trouble over the state of the economy and a series of political scandals, has been strongly criticised over the havoc.
"The whole country was delivered to chaos by an irresponsible government," the Eleftherotypia daily said in an editorial Tuesday. The top-selling Ta Nea added: "The police were absent from nearly all locations where vandalism occurred."
The violence has showcased the organisational capacity of urban radicals and the failure of the government to crack down on them, critics said.
Criminologist Ioannis Panoussis said: "There is a well-functioning mechanism in place," with the Internet and mobile telephones speeding up the troublemakers' capacity to react, Panoussis said.
"Because this time it connected with the spontaneous anger of the youths, the scale of the incidents vastly expanded," he added.
Social and economic factors also shape the anarchist movement, according to lawyer Dimitris Beladis, who specialises in urban troubles.
"It is the detonator of a sort of social explosion due to economic insecurity that affects many youths and those who are unemployed or badly paid," Beladis said.