A car bomb has exploded outside the Athens Stock Exchange, injuring one person and damaging eight cars.
Meanwhile, a second, smaller bomb outside a government building in the northern city of Thessaloniki also caused damage.
Despite the attack, the head of the Athens stock exchange said it would remain open.
A car bomb blew up outside the Athens stock exchange on Wednesday. A woman on her way to work was hit by flying glass. About eight vehicles nearby were damaged.
The police said the bomb was placed in a stolen van that had been parked on a side street outside the building.
But they could not immediately confirm how the bomb had been detonated, or what type of explosives had been used.
Soon after, a second bomb hidden in a telephone exchange box outside the Ministry for Macedonia and Thrace, in the northern city of Thessaloniki, exploded, causing minor damage.
Both attacks were preceded by warnings.
The Greek newspaper, Eleftherotypia, said it received an anonymous call warning of the attacks before the explosions, but said there had been no claim of responsibility.
A series of bombings and arson attacks have plagued Greece since police shot and killed a teenager in December.
The shooting sparked Greece's worst riots in decades, with protesters claiming the government was incapable of protecting its citizens.
(CCTV September 3, 2009)