The Bharatiya Janata Party (BJP) on Friday sought a CBI inquiry into the collapse of a flyover here that killed 23 people, and said the corrupt nexus between the West Bengal government and the opposition has been exposed."It is an act of fraud protected by the state government. The nexus of corruption between the Trinamool Congress and the Left party which is in the opposition has been exposed," union Minister of State for Minority Affairs Mukhtar Abbas Naqvi told reporters.He said the state government has deliberately tried to protect the fraud involved in awarding of contract for building the Vivekananda Road Flyover in Posta area that collapsed."It is clearly visible that the contract was given to a black-listed company and the work was not completed on time. We seek a CBI inquiry into the entire matter," said Naqvi.The flyover's foundation was laid in 2008 and work began in February 2009. It was to be completed by 2010, but continued to be incomplete until it collapsed on Thursday.