LONDON (Reuters) -British police said a fire which caused Heathrow Airport to close for 18 hours last week was no longer being treated as a potentially criminal matter.

There is no evidence to suggest the substation fire that shut down Heathrow airport was suspicious, police say. The fire, which broke out in Hayes on Friday, resulted in the closure of Britain's busiest airport for a day. Police say the fire was no longer being treated as a "potentially criminal matter", following an investigation.

British police said the substation fire which caused Heathrow Airport to shut down for 18 hours last week was no longer being treated as a potentially criminal matter after inquiries found no evidence to suggest the incident was suspicious.

Heathrow executives are defending their response to a fire that shut down Europe’s busiest air hub for almost a day.

London’s Heathrow Airport closed on Friday after a fire at a nearby electrical substation, resulting in hundreds of flight cancellations.

Heathrow Airport faces mounting pressure from the world’s biggest airlines after the power outage shutdown grounded hundreds of flights. Around 200,000 travellers were stranded in the UK and worldwide following the substation fire near Heathrow,