The seven-kilometre first line of Bangalore metro rail was thrown open for commercial operations on Thursday even as the Centre assured support to the proposed Rs 23,800 crore second phase covering a distance of 72 kilometre. Urban Development Minister Kamal Nath flagged off the inaugural run of Namma Metro (Our Metro) amid much fanfare at this technology hub of 85 lakh residents,became the first city in the south to get a mass rapid transit system. The seven-kilometre stretch - from Mahatma Gandhi Road to Baiyappanahalli - with six stations,costing Rs 1,540 crore,is part of the Rs 11,609 crore first phase covering 42.3 kilometre,construction of which is on fast-track and is expected to be completed by December 2013. Karnataka has prepared the second phase,and Kamal Nath in his address,urged the state government to clear it expeditiously and promised the Centre's full support to it. Chief Minister D V Sadananda Gowda said the second phase proposal would be approved in the next Cabinet meeting. Kamal Nath said the Union government is planning metro rails in all cities with a population of over 30 lakh. A project report is being prepared, he said. He said the Centre is giving thrust to development of suburban and satellite towns and announced that it would extend financial assistance in terms of water supply,sewage and waste management to Kanakapura town on Bangalore's outskirts.