Scientists say paintings in 11 caves in northwestern Spain, including the world-famous Altamira cave, are thousands of years older than previously thought.

Using a new dating technique, the scientists say they were able to establish that the cave art was more than 40,000 years old.

The study was conducted by researchers from eight European universities and research institutions. They took tiny samples of about 10 grams from thin layers of calcite - a carbonate mineral - that coat the paintings.

This coating is said to contain traces of radioactive uranium. By measuring how far the uranium had decayed into thorium, the scientists said they were able to determine the age of that layer. And the layer below it - that is, the actual painting - is thought to be even older.

If correct, it would be among the first evidence indicating that Neanderthals were Europe's cave artists.

"We are claiming the oldest reliably dated paintings in the world," said lead author, Alistair Pike, from Bristol University in the UK.

One of the biggest discoveries was the age of a number large red discs at El Castillo. They are thought to have been made by blowing pigment, and could be at least 40,800 years ago.

za / ji (AFP, Reuters)