The culprit behind a major sewage leak in the River Crane last October may never be known, after the Environment Agency said it had exhausted all lines of enquiry.

Trucks dumping soil beside the A312 in Cranford are believed to have cracked a water mains below, releasing harmful sewage sludge into the river.

The Environment Agency last year appealed for information about vehicles entering the site, at the junction with Cranford High Street, in an attempt to find the individual or company responsible.

But the eco watchdog today admitted it was no closer to discovering the offender, despite its best efforts.

"The Environment Agency's investigation into the cause of pollution incident on the River Crane in October 2013 has analysed all of the available information, including intelligence provided by members of the public and analysis of CCTV footage from TfL buses and images taken from nearby traffic cameras," a spokesman told getwestlondon.

"At this stage, it appears that all possible lines of enquiry have been exhausted."

Despite its criminal investigation having reached an apparent dead end, the EA still wants people to get in touch if they have any information about the incident.

It is particularly keen to identify the make, registration number or livery on an excavator or the lorry which dropped it off at the site, beside The Queen's Head pub, between September 26 and October 3.

The weight of the vehicles, or the material they deposited there, is believed to have caused the water mains to crack.

The resultant sewage leak killed a significant number of fish and insect life, the EA said at the time.

It came almost two years to the day raw sewage flooded the river, killing an estimated 10,000 fish. Thames Water was last month fined £75,000 and was ordered to pay nearly £95,000 in costs after admitting responsibility for the earlier incident.

Another sewage leak in the river last Wednesday (July 2) has been blamed by the utility firm on a blocked pipe, caused, it says, by customers pouring fat and other unsuitable products down their drains.

* Anyone with information about the sewage leak in October 2013 is asked to call the Environment Agency on 0800 807060.