Crimestoppers have said it would pay the reward for information leading to the arrest and conviction of those responsible.
This is an absolutely heartbreaking incident which has devastated and shocked the entire community.
It is impossible to imagine how Dr Shakoor, who survived the fire, is coping with the loss of his family.
Please come forward to the independent charity Crimestoppers so this truly awful crime can be solved.
Ann Scott added that people had "nothing to fear" by contacting Crimestoppers as all witnesses could remain anonymous.
More top news
Muslim leaders condemned the "heinous and appalling" Westminster terror attack.
Travis Frain is recovering in hospital and has posted a photo to Twitter of Prince Charles by his bedside.
Acting Commissioner Craig Mackey led new policemen and women in paying their respects at a passing-out parade in Hendon, north-west London.