New Delhi, Sep 13 : Former Union minister Raghuvansh Prasad Singh, who recently resigned from the Rashtriya Janta Dal (RJD), succumbed to post-Covid illness at All India Institute of Medical Sciences (AIIMS), New Delhi, on Sunday. Singh was suffering from a lung infection and was put on ventilator two days ago after his health deteriorated. He was admitted in the ICU unit of the hospital a week ago after contracting an infection in his lungs, a post-Covid illness he developed after contracting the Covid-19 disease. Singh had tested positive with the Covid-19 in June and was treated at AIIMS, Patna. 74-year-old Singh had resigned from the RJD a few days ago. He had written a series of letters to various politicians while undergoing treatment at AIIMS, Delhi. In one of his letters, circulated in the media, Singh had flayed the culture of dynastic politics and taken indirect potshots at family-rule in the RJD. Singh had represented the Vaishali constituency of Bihar was the national vice president of the RJD. /IANS