Residents on the Indonesian island of Java have been fleeing a vast plume of ash as an active volcano erupted for the second time in months.

Witnesses said a thick rain of volcanic ash from Mt Semeru was blotting out the Sun in two local districts.

No casualties have yet been reported and evacuations are underway, officials said.

Meanwhile, a monitoring body issued a warning to airlines of an ash cloud rising up to 15,000m (50,000 ft).

Thoriqul Haq, a local official, told Reuters that a road and bridge from the area to the nearby city of Malang had been severed.

"This has been a very pressing, rapid condition since it erupted," he said.

The Volcanic Ash Advisory Center (VAAC) in Darwin, Australia said the ash appeared to have detached from the summit and was drifting south-west.

The VAAC provides advice to the aviation industry about the location and movement of potentially hazardous volcanic ash.

The volcano, which rises 3,676m above sea level, previously erupted in January.

Mt Semeru is among Indonesia's nearly 130 active volcanoes.

Footage on social media showed residents running away as a giant ash cloud rose behind them.

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BPBD Provinsi Jatim dan BPBD Lumajang telah menuju lokasi untuk melakukan assesment dan evakuasi warga di sekitar Gunung Semeru. Silahkan mention jika ada yang dilokasi@PRB_BNPB pic.twitter.com/DYj8qIW23u

— jogjaupdate.com (@JogjaUpdate) December 4, 2021

Info saat ini bahwa jembatan Gladak perak putus. Tolong menginfokan kepada masyarakat yang akan melewati lokasi ini untuk berhati-hati pic.twitter.com/Cgap7SZwBz

— PRB Indonesia BNPB (Disaster Risk Reduction) (@PRB_BNPB) December 4, 2021