Greek police said they arrested a suspect Saturday over a series of letter bomb attacks targeting the country's creditors, one of which injured former prime minister Lucas Papademos earlier this year.
Police arrested a 29-year-old Greek man in the centre of Athens as he was leaving an apartment rented under an alias.
The man was reportedly carrying two pistols, a timer, explosive substances and gunpowder and various materials for the manufacture of timed devices, police said in a statement.
A police source said the man was known to police for his militant activities.
Papademos, who as prime minister from 2011 to 2012 agreed to punishing austerity measures to secure a bailout at the height of Greece's financial crisis, was injured when an explosive device detonated as he opened his mail in May.
The attack, which remains unclaimed, had a similar methodology to that used by Conspiracy of Fire Nuclei, a far-left group which in March mailed an explosive device that injured a secretary at the International Monetary Fund in Paris.
The group also claimed responsibility for a letter bomb, also sent from Greece, discovered at the Berlin offices of Germany's then finance minister Wolfgang Schaeuble.
The bombs contained gunpowder typically used in firecrackers, police said.
Eight other letter bombs, including those addressed to European Economic Affairs Commissioner Pierre Moscovici and then Eurogroup chief Jeroen Dijsselbloem, were intercepted in the aftermath of the Athens attack.
The search continues for other suspects, police said.
In 2011, a dozen members of Conspiracy of Fire Nuclei, many of whom were very young, were convicted of "participating in a criminal organisation" and are serving long prison sentences.
After years of crisis and austerity cuts, the Greek economy is still struggling, and experts have said that the country's continued crisis favours youth radicalisation.
In 2012, Papademos's government came under fire after it negotiated a huge write-down of the country's privately held debt, which led to Greek social insurance funds losing millions of euros.