A volcano in the Galapagos Islands has erupted for the first time in more than 30 years, spilling streams of bright orange lava and raising fears for the world's only colony of pink iguanas.

The Galapagos National Park Twitter account warned Isabela Island, where Wolf Volcano erupted at dawn, holds "the world's only population" of the critically endangered Conolophus marthae, also known as the Galapagos rosy iguana.

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But the park authority later said the iguanas' habitat on the volcano's north-west side appeared to be out of danger.

The iguanas, "which share the habitat with yellow iguanas and giant Chelonoidis becki tortoises, are situated on the northwest flank, which raises hopes that they will not be affected," it said in a statement.

The fiery streams of lava that trickled down the volcano Monday morning were on the opposite side, officials said.

A tourist boat passing by the uninhabited area informed authorities the 1,707-meter volcano was erupting.

Park officials then flew over the zone to assess the impact of the eruption.

Pictures released by the park show bright lava streaming down the volcano as a puff of smoke rises into the air and tongues of fire dart from the crater.

"The eruption generated a very large column of smoke that rose more than 10 kilometres into the air, and later drifted toward the southwest part of the volcano," Sandro Vaca of Ecuador's Geophysics Institute said.

"However, there has been no effect on residents."

Environmentalists voice concern over iguanas

The island's inhabitants live in Puerto Villamil, some 115 kilometres south of the volcano.

Mr Vaca said the volcano's activity could continue for several days, potentially causing further lava flows.

Park officials said the eruption posed no danger to tourists, and operations in the key tourism sector continued as normal in the area.

But environmentalists voiced concern over the pink iguanas, which were discovered in 1986 and established as a separate species after an analysis of their genetic makeup determined they were distinct from their cousins, the Galapagos land iguanas.

The iguanas are pink with charcoal stripes, and are listed as critically endangered by the International Union for Conservation of Nature.

Wolf Volcano last erupted in 1982.

Isabela Island is the largest in the Galapagos, the Ecuadoran archipelago made famous by Charles Darwin's studies of its breathtaking biodiversity, which was crucial in his development of the theory of evolution by natural selection.

The chain of 13 islands and 17 islets, which sits about 1,000 kilometres off the coast of Ecuador, is one of the most volcanically active regions in the world.

Isabela Island, which strides the equator, also has four other volcanoes: Darwin, Alcedo, Cerro Azul and Sierra Negra.

UNESCO, which has declared the Galapagos a World Heritage Site, warned the islands' environment is in danger from increased tourism and the introduction of invasive species.

AFP