New Delhi: The Delhi University Teachers' Association (DUTA) on Friday wrote to newly-appointed Human Resource Development (HRD) minister Prakash Javadekar highlighting the shortage of teachers in the varsity. DUTA president Nandita Narain said that the number of students in DU had increased over the years while thousands of posts of teachers were lying vacant. "Despite an increase in seats due to reservations for OBC students since 2007 and the promise of additional posts to universities, over 4,500 posts in DU remain vacant with teachers working on ad-hoc or guest basis," she said. She also said that the high teacher-student ratio was affecting the quality of teaching and global ranking of the university. "The UGC (University Grants Commission) has not released the second tranche of posts either, leading to extremely over-crowded classrooms and a very high student-teacher ratio that is not only affecting the quality of teaching but also the global rankings of our universities," said Narain. She added: "The denial of promotions to lakhs of teachers across the country since 2008 has already resulted in downgrading research and teaching in the universities, pushing the effective pay structure of university and college teachers way below that of All India Government Services, who have time bound promotions." Highlighting the plight of thousands of ad-hoc teachers, she complained about the "humiliating" conditions they (ad-hoc teachers) were working in at the university. "Highly qualified teachers are working in extremely humiliating, uncertain and exploitative conditions, having to seek renewal every four months, struggling for their vacation, salary, and being denied increments, maternity leave, medical leave etc.," she wrote while also seeking appointment with Javadekar to explain the crisis in the university. DUTA have been boycotting the admission and evaluation process at the university in protest against the new UGC norms to ascertain their academic performance.