A booby-trapped car exploded outside the Bank of Greece in central Athens early Thursday without injuring anyone, hours before Greece was due to return to the debt markets after a four-year absence.
The vehicle, a stolen Nissan packed with 75 kilograms (165 pounds) of explosives, blew up around 0255 GMT as it was parked on the pavement facing a central bank building near headquarters, police said.
Internet news website Zougla and the Efymerida ton Syndakton newspaper were informed of the planned attack by telephone one hour beforehand.
The blast came on the day Greece was due to sell bonds on the international markets for the first time since 2010 and a day before German Chancellor Angela Merkel was due to arrive in Athens.
Athens found itself frozen out of debt markets in 2010 after it revealed its public accounts had been falsified, and was forced to seek a bailout from the European Union and International Monetary Fund (IMF) to avoid defaulting.
The government announced on Wednesday that it would sell five-year bonds, with one of the banks running the deal saying Greece was expected to sell bonds worth at least 500 million euros ($690 million).
The last issue of five-year bonds four years ago had an interest rate of 6.1 percent, but experts believe that Greece might pay investors a rate of return as low as 5.0 percent this time.
Athens' move was welcomed by the IMF, which along with the European Union and the European Central Bank has provided monetary support for the troubled economy.
In return for the bailout funds, Greece has had to institute a host of deeply unpopular reforms including streamlining its bloated public sector, moves that have sparked regular strikes and protests in a country suffering a sixth straight year of recession and with a staggering 28-percent unemployment rate.
The announcement of the return to debt markets came on the same day that protesters launched the first anti-austerity strike of 2014, following five general strikes the previous year.
The strike shut ferry services to the country's world-famous islands, disrupted air travel and closed pharmacies and government offices.
The so-called "troika" of the European Union, the European Central Bank and the IMF first bailed out Greece in 2010 with a programme worth 110 billion euros.
When that failed to stabilise the economy, they agreed a much tougher second rescue in 2012 worth 130 billion euros, plus a private-sector debt write-off of more than 100 billion euros.
The government of centre-right Prime Minister Antonis Samaras is currently in talks with the creditors over the latest instalment of the bailout, with loan payments worth some 8.5 billion euros ($11.8 billion) pending.
According to reports, the creditors are pushing for additional civil-service layoffs and changes to a 1982 law on strikes to reduce their frequency.