MEXICO CITY (AP) _ A huge, mushroom-shaped cloud of steam and ash erupted from the Popocatapetl volcano on Monday, leaving a seemingly motionless cloud clearly visible from the capital 50 miles to the northwest.

Robert Quass of the National Center of Disasters Prevention told The Associated Press that the eruption was ``a sporadic emission, a `poof.' Seismologic activity remains very low and there is no cause whatsoever for alarm.''

He said steam and ash went about 3 miles into the air.

Puebla's State Civil Protection System remains on alert after similar brief activity last week, said its director, Guillermo Melgarejo Palafox. But there were no reports of evacuations from villages at the base of the 17,887-foot-high snow peak.

He told the government news agency Notimex that winds and possible rains could deposit some of the ash on the villages, some of which were evacuated during heavier activity in December of 1994.

Popocatapetl's last major eruption was in 1664.