No further attempts will be made to rescue a humpback whale who has gotten repeatedly stuck off Germany's Baltic coast, officials said on Wednesday, as experts believe the animal will not survive its week-long ordeal.

Till Backhaus, environment minister for the north-eastern Mecklenburg-Vorpommern region where the whale is currently stranded, said a restricted zone has been established around the animal to allow it to die in peace as there was no more hope of freeing it.

"We did everything we could to give it a chance. This is a unique tragedy. But it chose this path for himself," the minster said.

A days-long saga to guide the animal back to deeper waters began on March 23, when the whale was first spotted stranded on a sandbank off Germany's Timmendorfer Strand resort.

The 12- to 15-metre-long animal managed to free itself a few days later after rescuers dug a channel in the surrounding sand using a floating dredger.

But instead of moving west towards the Atlantic, its natural habitat, it was spotted heading east and repeatedly got stuck in shallow waters again.

The whale is currently stranded in the Bay of Wismar, where it is expected to die, according to Burkard Baschek, scientific director of the German Oceanographic Museum.

Chances that the whale will free itself again are very slim, he said, noting that it has become significantly weaker.

The animal's breathing rate was very irregular on Wednesday morning, with intervals of more than four minutes at times and the whale is keeping its pectoral fins close to its body, according to the expert.

"The reaction to us, to our presence, was virtually zero," said Baschek.

Meanwhile, the water level in the bay is expected to continue to fall by around 10 to 15 centimetres, he added.

"We would have to encourage it vigorously [to free itself], which would be futile because it no longer has the strength," Baschek said, adding that any attempt would amount to animal cruelty due to the slim chances of success.

Citing "respect for nature," Baschek said rescuers had decided that "at some point we must let it go."