Volunteers who have donated their time to help a humpback whale which got turned around off Germany's Baltic coast have received death threats now that it looks like the giant mammal might not survive its ordeal.

“Regrettably, since it became clear that the animal could not be saved, hostility towards those involved in the rescue operation has been on the rise – even to the point of death threats,” said Till Backhaus, environment minister for the north-eastern Mecklenburg-Vorpommern region where the whale is currently stranded, according to a statement.

"Of course, I understand that the situation is very emotional for people," Backhaus continued. "But I do not accept that staff members are being threatened in their private lives."

If statements constituting a criminal offence are made, whether on social media, via notes left in letterboxes or by email, such behaviour will be reported to the police, he added.

The 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 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.

Meanwhile, according to the state ministry, the whale is being monitored around the clock by the water police and a whale-watching team on land. Fire brigade personnel have been repeatedly spraying the animal with water throughout the day.

“We will continue to look after the animal – right to the end," he added.