ATHENS, Greece: A bomb exploded outside a Bank of Greece building in central Athens before dawn Thursday, causing some damage but no injuries.
The blast came hours before Greece was to return to the international bond markets for the first time in four years, and a day before German Chancellor Angela Merkel was to visit Athens.
The explosion was heard throughout the area, a largely commercial zone which is one of the Greek capital's most central, a few blocks away from the Greek parliament. It was preceded by two anonymous calls to a news website and a newspaper warning that a bomb had been planted in a car outside the central bank building.
As dawn broke, television footage showed the charred remnants of a car in the middle of the street, with only two wheels still recognizable. Debris was strewn around. Forensic experts in white coveralls began combing through the blast site and inspecting the wreckage.
Police cordoned off all roads leading to the area. Gaggles of office workers unable to access their offices gathered in nearby cafes.
A police officer at the scene, who spoke on condition of anonymity because he was not authorized to speak to the media, said the bank building and surrounding buildings had suffered some damage - mainly broken windows.
The news website that received one of the anonymous calls at 5:11 a.m. local time (0211 GMT) said the caller warned a bomb containing 75 kilograms (150 pounds) of explosives had been planted in a car and would explode in 45 minutes' time. The explosion occurred at about 6 a.m.
The attack comes as financially stricken Greece returns to borrowing on the international bond market. The country announced Wednesday it was issuing a five-year bond - its first since it became locked out of international markets in 2010.
The government has hailed the return to the bond market as proof that the country is emerging from its deep financial crisis.
"The evident target of the attackers is to change this image, and change the agenda," government spokesman Simos Kedikoglou said on an early morning television news show. "We will not allow the attackers to achieve their aim."
Since 2010, Greece has relied on funds from an international bailout, in return for which it has imposed deeply resented spending cuts, tax hikes and labor market reforms. Greece's economy has shrunk by a quarter, while unemployment hovers at 28 percent.
Greece has a long history of domestic militant groups who plant usually small bombs late at night that rarely cause injuries. Although the country's deadliest terrorist group, November 17, was eradicated and its members jailed in the early 2000s, several newer groups are still active.
One of the November 17 members, however, vanished while on furlough from prison in January. Another two suspected members of a different group, Revolutionary Struggle, vanished during their trial in 2012. They had been released after serving the maximum 18 months in pre-trial detention. That group is best known for firing a rocket into the U.S. Embassy in Athens and bombing the Athens Stock Exchange.