New Delhi, September 1Alarmed by the drive against graft, some politicians are joining hands to protect the corrupt, Prime Minister Narendra Modi said on Thursday.Lays stone of Kochi Metro Phase-IIPM Narendra Modi on Thursday laid the foundation stone for Phase-II stretch of the Kochi Metro rail project and the redevelopment of three railway stations in Kerala — Ernakulam Junction, Ernakulam Town and Kollam. The phase-II stretch of the Kochi Metro will have a length of 11.2 km and covering 11 stations.Modi, who was addressing a public meeting in Kochi in Kerala, asked people to be watchful with regard to these politicians. “People of the country, including those in Kerala, should shun these politicians,” the Prime Minister said.While speaking on corruption, Narendra Modi, however, refrained from taking name of any individual or party.The Prime Minister said corruption was the biggest challenge faced by the country. Because of corruption, youths cannot realise their aspirations. Corruption is also the biggest hindrance for fast-pace development, he said.”While speaking from the ramparts of the Red Fort also on the occasion of Independence Day, I said it was time that a decisive battle against corruption was fought,” Modi said.”As action is being taken against those indulging in corruption, it is leading to a new polarisation of political forces in the country. Some political parties have come out in the open and trying to put up a united front to protect the corrupt,” Modi, who was addressing the crowd with the help of an interpreter, said.The Prime Minister said he was happy to note that people of Kerala were looking at the BJP with fresh hope and counting on the promise that a BJP government would bring positive change in the state.