The 12th century key to the Kaaba in Mecca, Saudi Arabia, the holiest site in Islam, is seen in this undated handout photograph released in London on Thursday.  It sold for 9.2 million pounds late on Wednesday, setting a new record for an Islamic work of art at auction.
Photo: Sotheby's/Reuters

LONDON - A 12th century key to the Kaaba in Mecca, Saudi Arabia, the holiest site in Islam, has sold for STG9.2 million ($A19.57 million), setting a new record for an Islamic work of art at auction.

The Abbasid period key, made of iron and measuring 37cm long, sold at Sotheby's in London for more than 18 times its pre-sale estimate and was bought anonymously. It is the only known example to remain in private hands.

The key, one of the ultimate symbols of religious power, is engraved with the words: ''This is what was made for the Holy House of God during the time of our lord the Imam son of Imam al-Muqtadi Abu Ja'far al-Mustansir Abu'l-Abbas 573.''