SriLankan Airlines has announced the cancellation of flights UL 503 (Colombo to London) and UL 504 (London to Colombo) on 21 March 2025 due to a fire at a nearby electrical substation at Heathrow Airport. 

The airline is closely monitoring the situation and will resume flights once the airport reopens. 

Affected passengers can contact SriLankan Airlines for assistance.