KUALA LUMPUR, Feb 26 — Petroliam Nasional Bhd (Petronas) today reported a group loss after tax of RM21.0 billion for the financial year ended December 31, 2020 (FY20) due to net impairment losses totalling RM31.5 billion -- its biggest so far -- compared to a profit after tax (PAT) of RM40.5 billion in 2019.