Mannheim, Germany - Germany's Ufo hotline has been inundated with thousands of calls from people who have mistaken glowing lights in the nighttime sky for alien space objects.

The red-gold lights were in fact balloons that have become the latest festive season fad, according to Werner Walter of the Central Research Network for Unusual Sky Phenomena (CENAP).

The sightings were "nothing but hot air," said the Ufo expert, referring to the sky lanterns which have been sold for the first time at Christmas markets and garden centres across the country.

The miniature hot-air balloons, nothing more than a paper lantern suspended over a naked flame, provided "a silent alternative" to the traditional fireworks let off to mark the start of the New Year, Walter said. (dpa)