Egyptian authorities have started an investigation into Christie’s London upcoming sale of a 3,000-year-old statue of Tutankhamun’s head after concerns were raised that the bust might have been stolen from Karnak temple in Luxor.

The Egyptian brown quartzite head of Tutankhamen is expected to lead the auction house’s The Exceptional Sale in London on 4th July, carrying an estimate of £4m (US$5m). It portrays the young pharaoh as the God Amen, the most important deity of the New Kingdom.

Over 3000 years old, the bust is sold from the Resandro Collection, one of the world’s most renowned private collections of Egyptian art. According to the auction house, the present lot was acquired from Heinz Herzer, a Munich-based dealer in 1985. Prior to this, Joseph Messina, an Austrian dealer, acquired it in 1973-74 from Prinz Wilhelm von Thurn und Taxis who reputedly had it in his collection by the 1960s.

Yet, Egyptian officials fear the statue was taken from the Karnak temple complex, an ancient Egyptian temple precinct located on the east bank of the Nile River in Thebes (modern-day Luxor).

Dr Zahi Hawass, former Egyptian minister of antiquities, believes that the statue left Egypt in 1970. Egyptian officials have called on Christie’s to prove the statue left the country legally. Egypt’s ministry of antiquities reiterated Egyptian officials’ demand for documents showing proof of ownership.

“Ancient objects by their nature cannot be traced over millennia,” said the spokeswoman for Christie’s. She said the statue was previously widely exhibited, and that Christie’s informed the Egyptian embassy in London before the sale.