Clashes briefly broke out Thursday between riot police and protesters in central Athens during the first general strike since the country's left-led government initially came to power in January.

Youths broke away from a protest march by thousands as it passed outside parliament and threw Molotov cocktails at police who responded with tear gas and stun grenades. Demonstrators scattered, but calm returned within the hour.

Nearly 25,000 people participated in three separate demonstrations in central Athens, according to police figures, to protest a new round of bailout-related tax hikes and spending cuts. Another 10,000 marched without incident through the country's second largest city of Thessaloniki.

The 24-hour general strike has caused widespread disruption to public services.

The Athens metro and suburban railway shut down while bus, trolley and train routes were reduced and ferries remained tied up in port, severing connections between islands and the mainland. More than a dozen domestic flights were cancelled.

Greece Bailout Strike

Riot policemen try to avoid petrol bombs thrown by protesters during a rally in Athens, Thursday. Clashes broke out between riot police and youths during the first general strike since the country's left-led government initially came to power in January. (Petros Giannakouris/Associated Press)

The strike closed museums and archaeological sites, including the Acropolis, as well as state schools and pharmacies. Hospitals were functioning with emergency staff, while many privately owned shops also shut down.

Prime Minister Alexis Tsipras' left-wing Syriza party, which leads the governing coalition, has backed the strike.

The party's labour policy department called for mass participation to protest "the neoliberal policies and the blackmail from financial and political centres within and outside Greece."

Journalists also walked off the job, pulling news bulletins off the air except to report on the strike. News websites were not being updated, while no Friday newspapers were to be printed. Lawyers, too, were scaling back their work.

"They've deprived every Greek of hope for the future," said Katerina Kassimati, who works at a municipal preschool and was among the protesters. "We're of a certain age. The children that are left behind have no future."

Workers were protesting austerity measures imposed as part of Greece's third bailout — a three-year deal under which Greece will gradually receive up to 86 billion euros in rescue loans from its partners in the 19-country eurozone in return for passing a raft of spending cuts and tax hikes.

Greece Bailout Strike

A man walks in a depot of urban railway early into the 24-hour strike called by labour unions. (Thanassis Stavrakis/The Associated Press)

Tsipras, who won re-election in September, signed up to the bailout in a dramatic policy change despite initially campaigning vigorously against bailouts and their accompanying austerity conditions. He has said he had no choice but to agree to the deal to prevent Greece from defaulting on its debts and being forced out of Europe's joint currency.

"I believe strikes can turn into a boomerang for the worker, but there are times when people need to react," said 61-year-old Yannis Nikolaidis as he marched in the protest near parliament. "This is the time when people need to react. Enough already with the taxes, enough with the double talk. They need to let us breathe."

The government is currently locked in negotiations to reach an agreement on the disbursement of a 2 billion-euro installment, as well as 10 billion euros set aside for the recapitalization of its banks.

While Greece has met many of the requirements, it remains at odds with creditors over how to deal with non-performing loans and the repossession of homes whose owners have fallen into arrears on mortgage payments.