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.
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Mayor of London Sadiq Khan is backing the scheme.
A spokesperson said the lightning strikes had left the "aircraft fuelling system unavailable."
Nearly 1,000 properties have been left without power, and road users have been warned of potentially hazardous conditions.