PALU (AFP) - Indonesian conservation officials are racing to locate and rescue a saltwater crocodile that has had a motorbike tyre wrapped around its neck for more than a year on the island of Sulawesi.

The stricken crocodile, measuring around 4m long, has been regularly spotted in a river running through Central Sulawesi's capital, Palu, since 2016.

But a recent video shot by a local showed the reptile gasping for air with officials fearing the tyre is slowly killing the beast.

Conservationists believe someone may have deliberately placed the tyre around the protected animal's neck in a failed attempt to trap it as a pet.

The animal has recently been spotted swimming under a bridge in Palu with excited locals trying to take selfies with the croc in the background.

"In the past year, we saw that there's still enough room for the crocodile's neck to move around," head of the local conservation agency Haruna, who like many Indonesians goes by one name, told AFP on Thursday (Jan 11).

"But we are not going to wait until the tyre strangles the animal. We will rescue it."

Mr Haruna said the agency lacked proper equipment to rescue the animal, adding that their attempts to locate the animal has so far proved fruitless.

Authorities are also opposed to using tranquiliser darts on the animal, fearing it might disappear back into the river that is home to more than 20 crocodiles before the drugs take effect.

Instead Mr Haruna said his team has built an iron trap which will be placed inside the river when the water level is low.

"We will definitely save the crocodile but at the same time I also need to consider my men's safety," he said.

The huge Indonesian archipelago is home to a vast array of exotic wildlife, including several species of crocodile.