Bundesbank chief Jens Weidmann says he is opposed to giving Greece more emergency loans, charging the new government in Athens with frittering away a lot of trust.

"Until the autumn, an improvement in the economy had been discernible. But the new government has gambled away a lot of trust," Weidmann said in an interview with the weekly Focus that was released on Friday.

Greek Prime Minister Alexis Tsipras said Saturday that a hard-fought deal with European creditors ends austerity, but the "real difficulties" lie ahead. 

"We achieved much, but we have a long and difficult road ahead," Tsipras said in a nationally televised address hours after the deal was announced.

Greece and the EU must act quickly to end turbulence on the markets following the election of an a new anti-austerity government in Athens, senior commissioner Jyrki Katainen said Wednesday.

"We need to start working together very soon because the commitments haven't changed and time is running out," Katainen, vice president of the European Commission for jobs, growth and investment, told a press conference in Brussels.

At least four people were arrested in Athens on Saturday as part of a probe into a jihadist cell that was dismantled in Belgium this week before it could carry out any attacks, a Greek police source said.

Greece's anti-terror police were seeking to determine whether those arrested included Abdelhamid Abaaoud, the 27-year-old suspected mastermind of the cell who according to media reports may have been planning the foiled attacks from Greece.

The U.N. Security Council on Saturday condemned the night-time gun attack on the Israeli embassy in Athens and stressed the need to catch the perpetrators.

In a unanimous statement, the 15-member council "condemned in the strongest terms the terrorist attack against the Embassy of Israel in Athens, Greece, on 12 December, involving dozens of shots fired at the Embassy building, and underlined the need to bring its perpetrators to justice."

Greek police on Friday said a far-left group was likely responsible for a night-time gun attack on the Israeli embassy in Athens that saw the building sprayed with gunfire but no one hurt.

Two Kalashnikov assault rifles used in the attack had been used in a similar attack on the residence of the German ambassador last December by the People's Fighter Group, a police source said.

Acclaimed Greek author Menis Koumandareas, found dead in his Athens home over the weekend, was beaten and strangled, autopsy results showed Monday.

The author, who lived alone in the working-class district of Kypseli, also had wounds on his face and abdomen, a police source said.

Athens was assessing the damage Sunday after a night of protests that degenerated into violence on the sixth anniversary of the police killing of a teenager.

A total of 296 people were detained during the night, a police source said, while 43 suspected of involvement in the rioting in the Greek capital were due to go before prosecutors.

A strong 5.4 magnitude earthquake shook the Greek capital Athens early on Tuesday, the U.S. Geological Survey (USGS) said on its website.

The quake was centred southwest of the town of Prokopion on Evia, some 120 kilometres north of Athens, and was felt in the capital just past midnight (2300 GMT).

A 5.2-magnitude earthquake struck northern Greece early Saturday, the country's earthquake observatory said, with no reports of victims or major damage.

The tremor struck at 3:16 am (0016 GMT), with its epicentre 20 kilometres (12 miles) from the northern town of Arta and 249 kilometres northeast of the capital Athens, according to the observatory.