Public health care officials in the US are blaming the flu for dangerously low blood supplies around the country.

The American Red Cross said that donations are urgently needed because 27 of its 37 blood services regions have less than one day's supply of Type O blood, the so-called universal blood type.

All blood types are needed, but the Red Cross specifically asked for Type O because it can be safely transfused to most patients in emergency situations.

The shortage is nation-wide.

"This really goes from Boston to LA and hits the heartland," said Jacquelyn Fredrick, chief operating officer for the American Red Cross blood services.

Los Angeles, Philadelphia, Baltimore, Washington DC, Detroit, Nashville Tennessee and Columbia South Carolina are among the most severely affected areas.

Flu bug blamed

The Red Cross traditionally sees supplies decline around the holiday season as busy donors find it difficult to make time to give blood.

But the seasonal shortages were made more acute by an early outbreak of the flu that has hit some areas particularly hard.

At a blood centre in the US state of Illinois, 24 of 34 scheduled donors were forced to cancel their appointments due to illness.

The donors were part of a drive to collect blood platelets needed by cancer patients.