"The Prime Minister has sought Soren's resignation," Sanjayu Baru, media adviser to the PM, has said.Update at 1830 hrs: Union Coal Minister Shibu Soren was today convicted by a Delhi Court after it held him guilty of conspiracy in the kidnap and murder of his former private secretary Shashi Nath Jha twelve years ago.Four other accused, Nand Kishore Mehta alias Nandu, Shailendra Bhattacharya, Pashupati Nath Mehta alias Posho and Ajay Kumar Mehta alias Dillip, were also convicted in the case.Additional Sessions Judge B R Kedia found Soren, who is also chief of Jharkhand Mukti Morcha, guilty of kidnapping and hatching the conspiracy to kill his secretary.However, the court acquitted two others, Sunil Khaware and Asish Thakur. Soren, 62, was present in the court when the judge pronounced the verdict.Earlier, in his tenure in this government, Soren had to resign after a Jharkhand court issued a non-bailable warrant against him in connection with a case of murder during a protest agitation in the early 80's. He is on bail in the case and was reinducted into the Cabinet early this year.