ATHENS: A fifth day of running street battles between youths and police and a general strike plunged Greece into further turmoil on Wednesday despite a vow by Prime Minister Costas Karamanlis to restore order.

As tests reportedly showed the shooting of a schoolboy that sparked the riots may have been caused by a ricochet bullet, protesters hurled petrol bombs outside a court where two police officers arrested over the killing appeared.

Demonstrators battled security forces outside the Greek parliament as the nationwide strike halted flights in and out of the country and closed banks, schools and some hospital services.

Hundreds of police defended the parliament building against thousands of demonstrators angered at the death of 15-year-old Alexis Grigoropoulos, who are now turning their sights on Karamanlis's right-wing government.

The controversy heightened with initial results from a post-mortem indicating he was killed by a bullet ricochet, legal sources said.

According to forensic experts and independent experts acting for the Grigoropoulos family, the bullet "is a bit deformed, which showed the bullet touched a hard surface" before entering the boy's chest.

Grigoropoulos was allegedly among youths who threw stones at a police car on Saturday in a district of Athens known as a stronghold for political radicals.

Initial witness accounts said he was hit three times in the chest. His death set off nationwide unrest, including clashes at his funeral on Tuesday when riot police battled youths near the cemetery.

As the two officers arrested over the shooting went before a magistrate for questioning, protesters hurled two petrol bombs outside the courthouse.

The petrol bombs were thrown as the lawyer for the police officers, Alexis Kouyias, was preparing to talk to reporters. Police said the youths who threw the bombs were friends of the dead boy.

In other parts of the capital, demonstrators hurled fire bombs, pavement slabs, tangerines, water bottles and other missiles in the latest street battles. Riot police fired back tear gas as youths taunted them as "assassins".

Athens was rocked by disturbances almost through the night and similar troubles were reported in the northern city of Salonika where more than 80 shops and 14 banks were damaged.

In the city of Patras, at least 500 protesters laid siege to the police headquarters well into the night.

There have also been protests outside Greek embassies in other countries and around a dozen Turkish left-wing protesters daubed red paint over the front of the consulate in Istanbul on Wednesday in a show of solidarity.

Anger at the police has been compounded by growing public frustration with the Karamanlis government over its economic policies and a string of recent scandals.

"This death was the catalyst for many grievances," said 18-year-old farming student George Tzouvelekis, one of the protesters.

"Look how the banks are being attacked, because they have refused to lower interest rates amid the economic crisis... Everybody is fed up."

The general strike, called before the death of Grigoropoulos, brought public transport, schools, banks and most administrative offices to a halt. Airlines cancelled dozens of internal and international flights.

The Athens Chamber of Commerce and Industry (ACCI) said 435 businesses had been hit during the violence, including 37 that were completely gutted.

Items looted included cellphones, computer software and equipment, clothes, shoes, electronics, jewels and watches, the chamber said.

George Papalexis, the owner of a Zolotas gem store in the capital, said his business had sustained losses of 80,000 euros after a group smashed through a reinforced window and made off with jewellery.

"Personally I expect the government should resign," he said. "Very soon we'll see a change of government. It's a disgrace to see a city left to burn."

In a televised address, Karamanlis pledged up to 10,000 euros to stricken businesses, a tax freeze and government-guaranteed loans to rebuild buildings and property burnt in the troubles.

"The government is determined to consolidate the feeling of public safety and to help businesses get back on their feet," he said.

Despite the turmoil, Karamanlis's office said he would attend a European Union summit in Brussels this week. The opposition has demanded the government resign and the demonstrators outside parliament chanted "Sack Karamanlis". - AFP/so/de