Thousands of demonstrators surrounded the Greek parliament building in Athens on Thursday for the second day of a 48-hour general nationwide strike that has paralyzed the country. Up to 50,000 people attend the rally called by labour unions and Left parties, according to estimates by local media. They protested peacefully, as the assembly prepares to take a final key vote later in the day on painful fresh austerity measures demanded by foreign creditors in exchange of funding to avert default. In early afternoon groups of dozens hooded anarchists tried to approach the parliament and cause chaos, as it happened on Wednesday, when a demonstration of over 100,000 people- one of the biggest since the start of the debt crisis in 2009- was marred by extensive clashes between rioters and police. This time, peaceful protesters of the Greek Communist party and unions who had set up a cordon around the parliament, along anti- riot police, managed to push back rioters, when they started hurling chunks of marble and Molotov bombs again at police and the crowd. According to unofficial information so far up to 16 people have been injured, among them a protester who suffers from severe head injuries. About 50 people, among them 25 policemen, were injured during Wednesday\'s clashes that turned Athens into a battlefield for hours. On Thursday anarchists were forced to retreat when police fired tear gas and stun grenades and peaceful demonstrators did not leave Syntagma square this time. Representatives of the two umbrella unions representing public and private sector employees ADEDY and GSEE, which organize Thursday\'s rally as well, condemned violence, calling on people to stay on the streets of Athens and other main cities of Greece, to add pressure on the government. The Greek 300-member parliament approved on Wednesday evening in a first reading the new austerity draft bill with 154 votes, since all ruling socialist party deputies gave a positive vote. Despite reactions by some of them on particular articles, it is expected that the assembly will give the \"green light\" in a second and final vote on Thursday evening on measures that include fresh pay cuts, tax increases, the dismissal of 30,000 civil servants this year and changes on collective labor contracts. According to the government, Greece needs to pass the measures to secure the next tranche of vital aid by EU/ International Monetary Fund creditors. Without this aid, Greece could declare bankruptcy in November.