Two Javan rhinoceros calves have been spotted at an Indonesian national park, offering a rare sighting of one of the world's most endangered mammals.

The pair, ranging in age from three months to one year, were caught on footage snapped by camera traps in March at Ujung Kulon national park, the environment ministry said.

On the westernmost tip of Java island, Ujung Kulon is the last remaining wild habitat for Javan rhinos.

After years of population decline, there are believed to be just 73 of the rare mammals at the sanctuary, which comprises some 5,100 hectares (12,600 acres) of lush rainforest and freshwater streams.

Javan rhinos have folds of loose skin giving them the appearance of wearing armour plating.

They once numbered in the thousands across Southeast Asia, but have been hard hit by rampant poaching and human encroachment on their habitats.