Nearly 1,600 undocumented immigrants have been arrested in the Greek capital, Athens. 

Officials said an invasion of immigrants threatened debt-choked country's foundations. Over 6,000 people were questioned during a police crackdown and a total of 1,595 of them were arrested who will face deportation. 

Greece is struggling with a crippling economic crisis and austerity cuts, leading to rising social tensions.

Greek Prime Minister Antonis Samaras has named Greek economist Yannis Stournaras as the country's new Finance Minister, replacing 65-year old Vassilis Rapanos who resigned on Monday for health reasons. Stournaras, 55, is a respected liberal pro-reform economist who served as Development and Shipping Minister in the caretaker government that led Greece to the second round of national elections on June 17 after the first inconclusive polls in early May.

Later on Wednesday, he is due to hold his first meeting with Samaras and heads of two smaller parties in the new coalition government which took office last week. It is not clear whether Stournaras will attend the upcoming European economic union, the predecessor of the current euro zone.

European markets suffered a jittery session today as concern continued over Greece and Spain. Spain's main index is trading higher after losing more than two per cent earlier. Some investors moved money into German bonds, which are seen as low-risk. 

The oil price also fell, reflecting worries about the global economy. Confidence in European banks was undermined by rating agency, Moody's, which cut the credit ratings of 16 Spanish banks late yesterday.