PETROL poured down the drain caused a 'huge explosion' that sent manhole covers flying through the air.

Emergency service crews were called to Water Street in Accrington after panicked residents called 999 on Friday afternoon.

Now, after conducting an investigation, United Utilities has blamed the blast on highly-flammable fuel in the sewers.

The water board's spokeswoman, Helen Apps, said: "We believe someone poured petrol into the sewer network and it ignited. It's very fortunate that no one was injured. We will be doing further investigations to find out where the fuel came from."

Two crews from Hyndburn Fire Station and one from Blackburn were called out. After spending several hours on the scene, they allowed engineers from United Utilities to inspect the sewer using CCTV cameras.

No structural damage was found, but evidence of petrol was discovered.

A fire service spokesman said: "The explosion caused two very large manhole covers to fly in the air and residents reported a very loud explosion.

"Noone was injured and residents were allowed to stay in their houses.

"Fire crews were on the scene for around three hours."