Astronomers have found a cloud of frozen sugar near the centre of our galaxy, the Milky Way, it was revealed yesterday.

The discovery heightens the possibility of early building blocks of life originating in interstellar space.

Molecules of a simple sugar, glycolaldehyde, were detected in a cloud of gas and dust called Sagittarius B2, 26,000 light years away.

Observations indicated large quantities of the sugar frozen to a temperature only a few degrees above absolute zero, the point at which all molecular movement stops.

Glycolaldehyde consists of two carbon atoms, two oxygen atoms and four hydrogen atoms. This type of molecule is known as a two-carbon sugar. Significantly, it can react with a three-carbon sugar to produce the five-carbon sugar ribose - the molecule that forms the backbone of DNA.

The discovery adds to the growing evidence that the foundations of life can be traced to chemical reactions within interstellar clouds.

The theory is that a collision with a comet or a brush with a comet's tail could "seed" a young planet with the material needed to kick-start life.

Radio astronomer Dr Jan Hollis, from the US space agency Nasa's Goddard Space Flight Centre, in Maryland, said: "Many of the interstellar molecules discovered to date are the same kinds detected in laboratory experiments specifically designed to synthesise prebiotic molecules.

"This fact suggests a universal prebiotic chemistry."