The former New South Wales premier and foreign minister Bob Carr has written to UNESCO urging it to send a mission to the Blue Mountains to assess its world heritage status, warning it could be badly affected by the proposed heightening of the Warragamba Dam.

Mr Carr says the recent bushfire has burned more than 80% of world heritage-listed forests in the greater Blue Mountains and “destroyed very large numbers of threatened species”.

Experts in the field have also warned raising the dam wall would not necessarily remove the flood risk or lower the maximum flood height.