United Utilities has revealed it has discovered a 90-tonne fatberg lurking in a Liverpool sewer.

The 80-metre blockage consists of congealed fats, oils and sanitary products under the city’s Birchall Street.

Workers have dug under the road to access the sewer.

Engineers unsuccessfully attempted to shift the fatberg by using high-powered water jets and are now using picks and shovels in order to clear it.

The water company expects the work to take up to two months. Once cleared pieces of the fatberg will be sent away for recycling into biofuel.

Sam Fox, drainage performance manager at United Utilities, said: “We tried to clear the fatberg by jetting it with high pressure water, but this has not worked.

“We are now having to turn to pickaxes and shovels as we dig down onto the sewer so we can manually dig out the blockage.”

Fatbergs are an increasing concern for the UK’s wastewater industry, which spends up to £100 million a year clearing blockages.

United Utilities says it expects the total cost of removing this fatberg will be in “excess of £100,000”.

Over the past three to four decades a change in diet and lifestyles has resulted in an increased amount of fat, oil and grease in sewage.

Fox added: “Each year we tackle around 28,000 blockages in the sewers which serve the North West, costing around £10 million.

“There are lots of simple ways to safely dispose of leftover fat or grease, like letting it cool in a container and making sure you only put the ‘three Ps’ down your toilet – pee,  poo and paper.”

Elsewhere in the UK South West Water revealed last month that it had discovered its largest ever fatberg in a Sidmouth sewer under The Esplanade.

The 64-metre long “monster” fatberg lurking in the sewer networks of Devon is thought to be one of the largest found so close to the sea.

The congealed mass of fat, oil, grease and wet wipes is longer than six double decker buses and is expected to take around two months to remove. The company started clearing the blockage on 4 February.

In September last year Thames Water installed a “special edition” manhole cover to mark the first anniversary of the discovery of the 130-tonne Whitechapel fatberg.

The 250-metre long congealed mass of fat, oil, grease, nappies, wet wipes and other sanitary products blocked an east London sewer and took 13-weeks to remove.