Ecuadorian President Rafael Correa has declared a state of emergency over increasing activity in the Cotopaxi volcano near the capital of Quito.

Saturday’s decree gives authorities more flexibility in using government funds to deal with any problems, with officials having so far evacuating several hundred people as a precaution.

Eruptions beginning Friday have shot ash more than five kilometres into the sky, spreading fine grey powder over roads, homes and cars in the region as far as the capital, 50km to the north.

Presidential legal secretary Alexis Mera said further ash explosions and some pyroclastic flows on the volcano's western slopes on Saturday led officials to evacuate some nearby villages.

Cotopaxi is considered one of the world's most dangerous volcanoes due to a glacial cover that makes it prone to fast-moving volcanic rock and mud flows, known as lahares.

The almost 6,000 metre, snow-capped volcano, which last had a major eruption in 1877, is close to heavily populated area around Quito.

Authorities had already restricted access to the park that surrounds Cotopaxi and suspended ascents of the peak, which is popular with mountaineers.

AP