And the release of a parliamentary inquiry into a land scandal, which has also generated widespread anti-government sentiment, threatened to increase the pressure on Karamanlis' embattled right-wing government.

Police were guarding the capital's courts, where six of the 86 people arrested throughout the unrest overnight on Saturday were appearing before magistrates.

Around 100 youths were camped outside with a banner showing solidarity with "state hostages."

Just one firebomb attack was reported overnight in the student district of Exarchia, where 15-year-old Alexis Grigoropoulos died from a police bullet nine days ago.

Rallies were announced drawing university and school students to the Athens police headquarters from midday and again after dark. But protesters admitted that maintaining momentum was becoming difficult.

More than 100 schools were still occupied over the weekend, and pupils began blocking traffic around the education and defence ministries early Monday.

After protests dimmed across the Greek provinces, banks were targeted by youths in the central town of Volos overnight, while left-wing activists called for a rally in Larissa in solidarity with protesters facing magistrates.

At the spot where Grigoropoulos fell on December 6, an impromptu shrine drew hundreds of mourners Sunday night, with a sprawling mound of candles, football scarves, cigarettes and other mementoes left at the site.

Karamanlis was going ahead with a planned visit to Cyprus for the funeral of former Cypriot president Tassos Papadopoulos, who died of cancer on Friday.

The premier has rejected calls to quit, although opposition socialist leader George Papandreou on Sunday demanded fresh elections.

He told a PASOK party meeting that Karamanlis's government "ignores the calls of society, is incapable of steadily driving the country towards change and is afraid of the people... Its political time is finished."

A Sunday poll suggested most Greeks see violent protests over the past 10 days as a "popular uprising," not driven by "minority activists."

The influential Vatopedi Monastery in northern Greece is under investigation over a series of property swaps of valuable state land that lost Greek taxpayers millions of euros (dollars).

One of Karamanlis' closest advisers was forced to resign over the affair in October, with merchant shipping minister Georgios Voulgarakis quitting earlier after it was disclosed his wife had acted as notary in the transaction.

Ephraim was seen to have acted in contempt of the parliamentary commission looking into the scandal.