More snow, sleet to lash USA

A mammoth storm threatens to dump mounds of fresh snow, sleet and ice on about 100 million already winter-weary Americans, AFP reported.

Blizzard, winter storm and freezing rain warnings were issued for more than 25 states, from North Dakota and Colorado down to New Mexico, then up through Texas, Kansas and Missouri to the Great Lakes region and across Pennsylvania to New England.

The Federal Emergency Management Agency (FEMA) urged residents to prepare in earnest for the fury of the storm as it barrels eastward across the country.

"A storm of this size and scope needs to be taken seriously," said FEMA administrator Craig Fugate, who warned that "it's critical that the public does its part to get ready".

Fugate urged residents in storm affected regions to "check on your neighbours, especially the elderly and young children - those who can be most vulnerable during emergencies".

Scores of schools and government offices in the US Midwest were closed on Monday as freezing rain began to fall, threatening to turn roads into deadly ice rinks, and down power lines and trees.

Airlines warned of significant delays and cancellations, and offered customers a chance to rebook flights at no fee, AFP reported.