Indonesia’s Mount Sinabung has erupted more than 30 times, spewing lava and ash clouds over a wide area, officials said, with more than 26,000 people now forced to flee their homes.

Mt Sinabung, which lies in the northwest of Indonesia’s Sumatra island, sent hot rocks and ash 5 kilometres into in the air, spreading hot clouds over a 4.5-kilometre radius, said the Centre for Volcanology and Geological Hazard Mitigation.

Enormous clouds rose from the mountain, as thick layers of grey ash blanketed plantations and nearby houses.

With the volcano erupting regularly, many of those who have left their homes since Mt Sinabung started erupting in September have fallen ill, a local government official said.

“Some refugees are sick, coughing mainly, and they are also in need of clean water,” said Robert Peranginangin, a spokesman for Karo district.

Volcanoes are a regular threat for many living near their fertile slopes in Indonesia. Mt Sinabung is one of 129 active volcanoes in Indonesia that straddle major tectonic fault lines, known as the Pacific Ring of Fire.

It had been quiet for around 400 years until it rumbled back to life in 2010, and again in September last year.

In August 2013, five people were killed and hundreds evacuated when a volcano on a small island in East Nusa Tenggara province erupted.

The country’s most active volcano, Mount Merapi in central Java, killed more than 350 people in a series of eruptions in 2010.