EDIT CONTAINS 4:3 MATERIAL
Mexican authorities are keeping a close eye on the Popocatepetl volcano near Mexico City after it spewed a three-kilometre-long fume on Tuesday (May 14) morning.
Dramatic photos release by Mexican authorities showed the moment of the eruption.
The alert level for the towering volcano was raised to yellow phase three from yellow phase two, on orders from the country's Interior Ministry, at the weekend.
Civil protection authorities are keeping a close eye on nearby towns in case evacuations are needed. No evacuations have been ordered so far.
The lava dome of Popocatepetl, some 50 miles to the southeast of the capital, may expand and unleash increasingly powerful explosions of ash and lava, Mexico's National Centre for Disaster Prevention said in a statement.
It is the third-highest warning on the centre's seven-step scale.
This change in activity in the 5,450-metre (17,900-foot) volcano could provoke big explosions capable of sending incandescent fragments out over considerable distances, the centre added.
Popocateptl erupting (0:31)
May 15 - Authorities watching the Popocatepetl volcano near Mexico City. Rough Cut (no reporter narration). ( Transcript )