Anti-austerity activists are planning new protests in Athens' main square the day after a retiree publicly killed himself, leaving a note that blasted politicians over the country's financial crisis.

Many in the debt-crippled country see the 77-year-old retired pharmacist as a martyr, whose suicide symbolized the cumulative effect of over two years of economic pain imposed to secure international bailouts shielding the country from bankruptcy.

More than 1,500 people gathered at Syntagma Square hours after the suicide Wednesday, chanting "this was no suicide, it was a state-perpetrated murder," and clashing with riot police.

The retiree chose the morning rush hour to shoot himself in the head near a subway exit on the square — a focal point for protests and a stone's throw from parliament. The tree under which he died was quickly festooned with notes blaming government-imposed austerity for his death.

Dozens gathered on the spot Thursday, leaving flowers, Greek flags and candles on the grass.

In a suicide note published by local media, the man said he could not survive on his pension and expected Greeks to take up arms and "hang traitors" in the square.

'Political act'

"It was clearly a political act," said Petros Constantinou, organizer for the left wing Antarsya group that participated in Wednesday's protests. "The fact that a person reached the point of giving his life to change the situation shows ... where the policies of austerity and poverty have brought people."

A mourner cries at the spot where a man committed suicide at central Syntagma square in Athens. (John Kolesidis/Reuters)

"This is not just desperation, someone has given his life to stop these policies," Constantinou said. "I think it was a wake-up call, that things cannot continue this way, and he wanted people to rise up."

Greece has survived on rescue loans from its European partners and the International Monetary Fund since May 2010. To secure the cash lifeline, the country imposed harsh cutbacks, slashing pensions and salaries while repeatedly increasing taxes. A new round of belt-tightening worth about 7 per cent of Gross Domestic Product is expected to be announced in June.

The crisis has cost tens of thousands of jobs, sending unemployment to a record high of 21 per cent while one in two Greeks aged under 25 is jobless — amid a shrinking economy that is not expected to revive for at least two years.

Suicides are on the rise, although accurate figures are hard to access as not all are reported.

Police have recorded more than 1,700 such suicides and attempts since 2009, while the health ministry said suicides jumped 40 per cent in the first five months of 2011 over the same period in 2010, with analysts linking the surge to the pressures of economic hardship.

Prime Minister Lucas Papademos, and the heads of the two parties in his interim coalition government, quickly expressed their sorrow at the Syntagma shooting. Greece is heading for national elections next month, with anti-austerity parties polling high.

Even the influential Church of Greece stepped in Thursday, saying that while it frowns on suicide, the incident provoked "sorrow and sympathy."

"This suicide and other similar ones in the painful times of crisis we are going through deeply concern our society," a Church statement said. "Growing problems and the intensifying crisis cultivate despair and lead people to desperate acts while stripping them of their dignity."

Groups ranging from social media activists to schoolchildren have said they will join in the protests later Thursday.