This article is more than 11 years old

This article is more than 11 years old

Hundreds of students clashed with police in several Greek cities today during a third day of rioting, increasing the pressure on an already unpopular government.

Police fired tear gas at rioters in Thessaloniki, Greece's second largest city. Clashes were also reported in Crete, Corfu, and several other places, while in Athens, 13 police stations were damaged.

With a 24-hour general strike due on Wednesday against pension reforms and the government's economic policies, Greeks fear that general unrest could last for days.

More trouble was expected later tonight as the Greek Communist party called a rally, despite the arrest of two police officers for the shooting on Saturday night of a 15-year-old boy.

"We will not tolerate unacceptable and dangerous events prompted by the tragic incident," the prime minister, Costas Karamanlis, said in a televised statement.

Even before the violence at the weekend, the ruling Conservative party was already feeling the heat. Unpopular economic policies and allegations of corruption have seen the government sink in the polls.

Britain and Australia have urged tourists to take care when visiting Athens. Rioters remain barricaded at two university campuses there, and youths have blocked two main roads in the capital and an urban rail system.

Demonstrations also turned violent in Trikala, a small central Greek town where a policeman was reportedly injured and a rail route blocked.

Police fought running battles with demonstrators at the weekend, after the shooting of a teenager by police. Authorities have charged a 37-year-old policeman with murder for the killing of Alexandros Grigoropoulos, in Athens' central Exarchia district, an area known for lawlessness and drugs.

Grigoropoulos was shot in the left side of the chest and died before an ambulance transported him to a state hospital, health ministry officials said.

The police officers' association has apologised to the boy's family and the country's president, Karolos Papoulias, sent a telegram to his parents expressing his condolences.

"This death was a blow to the country," Papoulias said. "I am certain that those responsible will be held to account."

Police said 14 people were arrested in Athens over the weekend for public disturbances and looting. Health officials said hospitals treated 29 people with minor injuries from yesterday's violence.

"Under the circumstances I think we achieved the best possible result," said Panayiotis Stathis, a police spokesman. "Human life was protected, both that of the demonstrators and the police. That's the most important thing."

The violence – the worst Greece has seen in years - erupted late on Saturday and spread within hours to Thessaloniki, Greece's northern capital, its western port city of Patras and Chania on Crete. Helmeted and hooded demonstrators went on the rampage, venting anger and disaffection exacerbated by the economic crisis.

By last night, several areas including Athens's main commercial strip and the streets around its fabled polytechnic resembled a battle zone, with glass, rubble and broken mannequins on the footpaths.

Smoke filled the capital's skyline and shopkeepers rushed to clear up debris. Officials said more than 30 people were injured including police, firefighters and bystanders. Looting was rife.

Television stations showed stone-throwing youths erecting barricades in Athens. Police responded by firing teargas.

The rioters sought sanctuary in the grounds of the Polytechnic and Athens University, which traditionally have been off-limits to security forces since the collapse of military rule in 1974.

The crisis deepened yesterday in both Athens and Thessaloniki as thousands of demonstrators marched through the streets shouting anti-government slogans. "Down with the murderers in uniform," they shouted at the police.

"I've never seen anything like this," said Kostas Koskliouris, 42, standing outside the Benetton clothing store where he works. "So much of Athens is destroyed and it all happened in just a couple of hours."

The scale of the protests appeared to catch Greece's embattled centre-right government off guard. Angered and embarrassed by the killing of the teenager – the schoolboy son of a bank manager – the interior minister, Prokopis Pavlopoulos, immediately tendered his resignation, promising "exemplary punishment" for the police involved.

A police statement said an officer fired three shots after his car was attacked by 30 youths in Exarchia. A police official said the officer described his gunfire as warning shots but witnesses told Greek television he aimed at the boy.

The prime minister has publicly apologised to the father of the dead boy. "I know nothing can relieve your pain, but I assure you ... the state will act, as it ought to, so that yesterday's tragedy won't be repeated."

There is little sign that pleas for calm are being heeded. "Greek society has been besieged by a feeling of hopelessness; many don't believe in anything," said Stelios Bahis, 44, a former merchant marine engineer who works as a museum guard.

"It was great that the politicians we have today helped get rid of the junta in 1974. But ever since they've just created their own cliques of power and sidelined those who are not with them. People have had enough of the scandals, the corruption and especially the police, who we all know are not clean."