Timmy, the stranded humpback whale, found dead off Danish coast

Timmy, the young humpback whale who was stranded for weeks in shallow waters, has been found dead just off Denmark's coast, according to the Danish Environmental Protection Agency, just weeks after a controversial rescue effort set him free.

"The stranded humpback whale near Anholt is the same whale that was previously stranded in Germany and was the subject of rescue attempts," Jane Hansen, head of division at the Danish Environmental Protection Agency, told CNN on Saturday.

The agency confirmed the whale's identity after one of its workers found and retrieved the faulty tracking device that had been attached to him during his rescue attempt.

WORLD: Health experts 'very alarmed' as deadly virus breaks containment

LIVE UPDATES: Senator says Trump 'stupid enough' to fight Israel's war

"The position and appearance of the device confirm that this is the same whale that had previously been observed and handled in German waters," Hansen said.

Timmy was found on Friday near the island of Anholt – situated in the Kattegat Strait between Denmark and Sweden, about 130 kilometres from where he was released.

He was first spotted at the beginning of March in Wismar harbor, entangled in a fishing net, and had to be freed by emergency services.

Then, he became stranded at the end of March when he got lost in shallow water near Timmendorfer Strand, a town on Germany's north coast that gave him his nickname.

That prompted an extensive rescue effort, and widespread media coverage as the whale's ordeal was livestreamed around the world.

STATE OF ORIGIN LIVE: Ten debutants named as Blues and Maroons make gambles

But rescuers could not free the whale, and as his health declined, they stopped their efforts.

However, another privately funded rescue attempt, which directed Timmy to swim into a barge before shipping him out into the open sea, pressed ahead despite warnings from scientists that the whale was too weak to survive.

During the time he was stranded, he spent days barely moving, breathing irregularly and suffering from a bad skin condition caused by the Baltic Sea's low salt content.

Such warnings meant the rescue became mired in controversy.

WATCH: Horror moment fighter jets collide mid-air

To its critics, it represented a form of animal cruelty, causing the whale severe stress for no reason.

"I believe the whale will die very soon now," Thilo Maack, a marine biologist for Greenpeace, told the Associated Press in April as rescuers tried to set Timmy free.

"And I would also like to raise the question: What is actually so bad about that? … Yes, animals live, animals die. This animal is really, really very, very, very sick. And it has decided to seek rest."

NATIONAL: Taylor edges ahead of Albanese as preferred PM after 'difficult' Budget

But to others, like the province's environment minister, Till Backhaus, who allowed the private rescue attempt to go ahead, it was a normal response "to use even the smallest chance when a life is at stake," as he told AP.

There are no plans to remove Timmy's carcass, the Danish Environmental Protection Agency added, since it "is not currently considered to pose a problem in the area."

It urged people to keep a safe distance and not approach the whale for health reasons - and in case it explodes.

NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.

• Download the 9NEWS App here via Apple and Google Play

• Make 9News your preferred source on Google by ticking this box here

• Sign up to our breaking newsletter here