ATHENS (AFP) - The focus of widespread protests following the police killing of a teenager shifted to the scene of his death Saturday, after banks were attacked in Athens and another tense standoff with police. Alexis Grigoropoulos was killed exactly one week ago on the night of December 6, and radicals occupying nearby university buildings said they would gather over the weekend at the spot where the 15-year-old died. An edgy stand-off had developed earlier as some 2,000 demonstrators " mainly Athens Polytechnic students " squared up to police outside the Greek parliament on the eighth day of their dogged challenge to state authorities. Swelled by self-styled anarchists, students blocked off the central Syntagma Square after an earlier sit-down protest by around 300 school pupils ended peacefully, and mostly dispersed by around 6:00 pm (1600 GMT). As darkness fell, around 100 of the more militant among them continued to loiter " amid growing police frustration, going by one officer's conversation on his mobile and not least due to low stocks of tear gas. Student pamphlets also announced rallies planned in front of the Athens police headquarters on Monday and back at parliament square on Thursday, when school pupils and teachers are expected to back the protests. Demonstrators at the schools rally " with no security presence in evidence " held aloft a large banner at the rear bearing the inscription: "06/12/08, Alexis Grigoropoulos, I won't forget." About 2,000 youths also marched peacefully in Greece's second city, Thessaloniki, Saturday afternoon, a correspondent said, while police identified five banks attacked in Athens " underlining the link between the crisis and broader economic malaise. The overnight attacks on Greek and US banks, using gas canisters, also targeted a local party office operated by Greece's ruling conservative party. There were no victims, but firefighters had to extinguish blazes. Alongside neighbouring shops, two cars were burnt out in the busy Guizi and Exarchia areas of the city. The tone had changed after riot police again clashed with youths on Friday, but not the deeply-held anger which has emerged within the lower end of the 15-24 age group, one quarter of whom nationally remain unemployed. The latest protests come after Greek Prime Minister Costas Karamanlis dismissed opposition calls to quit while attending an EU summit in Brussels. "At this time the country faces a serious financial crisis... a steady hand on the helm is needed to deal with it," Karamanlis said. "That is my concern, that is the priority of the government, not scenarios about elections and successions. "The compassion with which all of us ought to treat the distress of young people cannot be confused with blind violence, with the activities of extreme elements." The offices of lawyer Alexis Kougias, representing two policemen awaiting trial over Grigoropoulos' death, were also trashed Friday. Elsewhere in Europe, demonstrators blocked traffic on the Champs-Elysees in Paris and hundreds marched in Berlin to show solidarity. The officer who shot Grigoropoulos says he killed the boy by accident out of self defence due to a bullet ricochet. A ballistics report, said to confirm that the handgun was not pointed at him, has yet to be released.