India\'s prime minister Manmohan Singh faced growing calls Thursday to sack a minister named in a police investigation into the latest alleged corruption scam to hit his administration. Singh has grappled with a string of government-linked graft scandals over the last year, including claims that the allocation of second-generation (2G) mobile phone licences cost the treasury $40 billion in lost revenue. Dayanidhi Maran, telecoms minister from 2004-07, was on Wednesday accused in a police court report of manipulating the 2G sale in favour of companies to which he was linked. Singh\'s upright image has been tarnished by accusations of widespread corruption within his government despite his repeated claims of having a \"zero tolerance\" policy toward graft. The allegations against Maran brought another day of critical front-pages for Singh, with many newspapers predicting Maran would be sacked or forced to resign ahead of an upcoming cabinet reshuffle. Maran, who is currently textiles minister, has denied charges that he forced the founder of the Aircel telecom group, C. Sivasankaran, to sell his stake in the group to another company which was close to the Maran family. Sivasankaran \"had been knocking at various doors but was left with no choice but to sell his shares to a Malaysian firm,\" a police lawyer told the Supreme Court on Wednesday. The police report lodged with the court said Sivasankaran had been prevented from gaining a telecom licence, but the Maxis Group, the Malaysian firm, was granted licences within six months of taking over Aircel\'s business. Opposition parties united to demand action over the graft allegations. \"The resignation of Maran has to happen. Certainly his position has become untenable,\" said Nirmala Sitaraman, spokeswoman for the main opposition BJP party. Maran, from the DMK regional party that is a key ally of the Congress-led government, was replaced as telecoms minister by A. Raja, who is also from the DMK party. Raja was forced to resign over the 2G licence scam and is in custody awaiting trial along with several top government officials and business executives.