Article published on the 2009-09-03 Latest update 2009-09-03 15:53 TU
The election is to take place barely halfway through the right-wing government's four-year term of office.
Karamanlis argues that he needs a fresh mandate to tackle the economic downturn, although official statistics announced today show that the country has avoided recession, with 0.2 per cent growth in the second quarter of the year.
"We have to clarify the political landscape and proceed with a series of essential measures to emerge from the downturn." Karamanlis said in a televised address on Wednesday.
"The year 2010 will be a difficult and decisive one, and so the Greek people must choose a government that can lead the country out of this crisis."
Correspondent John Psaropolos says this is one of two reasons Karamanlis has called the election now. He says the other is to do with the upcoming budget, presented in September.
"It's the first piece of political legislation to be presented in the Greek political calendar and in order to pass the budget you have to have the confidence of the rest of parliament," he said to RFI, "even though the ruling party can elect the budget through on its own."
Psaropolos says this means timing of the election is critical around the budget.
"What you want to avoid is the budget being used as a political football because you're in a pre-election period," he says.
The Prime Minister's decision has been expected for weeks. The government has been hit by corruption scandals, including a property deal with the influential Vatopedi Monastery that reduced the government's majority to just one seat in the 300-member parliament after Karamanlis sacked a rebel MP.
His government has been criticised for its handling riots last year and of fires which came close to Athens this year.
In June's European elections, his New Democracy Party was left with the second-worst EU vote in its history, while the opposition Socialists, Pasok, won their first victory in five years.