Fiery rocks have been spewing from the Popocatepetl volcano outside Mexico City for another night, with the worst eruptions coming just after midnight local time.

The authorities have been preparing for a potential evacuation of residents living on the slopes of the volcano.

Locals still remember the volcano's last major eruption in 2000, when thousands of people had to flee their villages.

Some locals schools have closed, while students in others were given surgical masks to protect them from the ash in the air.

Families with young children have been particularly worried about the evacuation plans, but officials say shelters are ready and equipped for all eventualities.