At least 1,000 people living near the Chaparrastique volcano have been evacuated as a precautionary measure after seismic activity increased at the volcano, Salvadoran civil protection authorities said Monday.

There was an explosion early Monday and the volcano then spewed reddish ash, officials said.

The Civil Protection Department said in a statement that an alert had been declared for the municipality of San Miguel, where the volcano is located. The city of San Miguel itself is 50 kilometres from the volcano. It is one of the largest cities in the Central American country.

The 2,129-metre volcano is about 145 kilometres east of San Salvador, the capital of El Salvador.

The volcano's last significant eruption was in 1976.