A whale which became beached on mud flats off the South Coast was put down yesterday after tests revealed it had suffered kidney failure during the ordeal.

Crowds of well-wishers lined the shoreline at Langstone Harbour, opposite Hayling Island near Portsmouth, Hampshire, as rescuers struggled to free the 26ft-long whale.

The northern bottlenose whale - the same species as the one which died after swimming up the Thames in central London two years ago - was first seen in difficulty in the shallow water on Thursday morning.

Marine experts manage to refloat the stricken whale after it became stranded on mudflats

The stressed whale struggled to right itself as it was led to shallow waters

But despite a desperate 12-hour rescue operation, it ended in failure last night as the whale, nicknamed Hayley after the island, lost its fight for life.

She became beached on mud flats during low tide on Thursday evening and had to be hosed down by fire fighters in a bid to prevent it becoming dehydrated.

Blood tests were taken before the whale eventually refloated in high tide yesterday morning.  

Rescue crews desperately tried to save the young bottlenose whale after it became stranded in mudflats overnight

An aerial view shows the dramatic rescue operation in progress

But the test results later revealed Hayley had suffered irreversible renal failure, and had also sustained muscle damage during the long hours stranded on land.

She was given a lethal injection when the low tide left it stranded on the mud again late yesterday afternoon. 

Faye Archell, director with the British Divers Marine Life Rescue, said the whale was administered with a fast-acting fatal strength anaesthetic, called Immobilon.

'The decision has been made based on medical grounds,' she said.

'It's the right decision for the whale. It's sick and distressed and it has come in for a second time. It has chosen to strand both times.'

A rescuer spent most of the morning hosing down the mammal which was stressed and dehydrated

More than 30 people were involved in the dramatic rescue attempt

Doctor Paul Jepson, a senior research fellow at the Zoological Society in London, led the team that treated Hayley.

He said that because the six-tonne mammal had been lying on hard land instead of floating in water, the whale had suffered damage to her muscles and vital organs.

This pressure is also likely to have triggered the release of toxins which contributed to the kidney damage, along with dehydration.

The northern bottlenose is a deep-diving whale and was a two-day swim away from the closest water of the depth it needs off the Bay of Biscay.

The species doesn't drink water and instead gets fluid from its staple food of deep-sea squid, which are not readily available in the English Channel.

The young adult may originally have been part of a pod, or larger group.

It is unclear why she ended up so far off course, but could have already become ill.

Despite all the attempts to save her, the whale suffered kidney failure

Dr Jepson said putting Hayley down was the most humane course of action.

Miss Archell also helped with the rescue of a stranded northern bottlenose whale along the River Thames in London in January 2006.

Named Willy after the whale in the movie Free Willy, the whale was renamed Wilma after a post-mortem examination revealed it was female. The probable cause of death was dehydration.

The bones have joined the Natural History Museum's national research collection of 2,500 whale, dolphin and porpoise skeletons.

The six-tonne mammal was said to be 3,000 miles (4,828 km) off course

The young adult is the same variety of whale which became stranded on the River Thames in 2006