Datuk Seri Najib Tun Razak says Yang di-Pertuan Agong Tuanku Abdul Halim Mu'adzam Shah explained to Tun Dr Mahathir Mohamad that he could not interfere in the efforts made by Parti Pribumi Bersatu Malaysia (PPBM).<br />The Prime Minister said he had been informed by Agong about the audience granted to Dr Mahathir, who is also PPBM chairman, at Istana Anak Bukit, Alor Setar, last week.