The etchings - a self-portrait and one depicting the artist's mother - were valued at about �219,000, a senior detective estimated.

The etchings and certificates of authenticity were stolen from Mount Eliza, south-eastern Australia.

The etchings are more than 300 years old and have been in the same family for seven generations.

The burglars removed the small etchings from the bedroom wall of the house.

"While the etchings have a substantial financial value, the also have extreme sentimental value to the family," said senior police investigator Craig Davis.

Earlier this month, an etching by the artist discovered in a charity shop bin in Befordshire was sold for more than �7,000.

The etching, Beggar Man and a Beggar Woman Conversing, was found by a paintings valuer on a visit to the shop in September.