The head of the German Museum in Berlin has rejected anew an Egyptian request to have the bust of ancient queen Nefertiti displayed at a Cairo exhibition.

The director of the museum said he fears that the bust would be disintegrated as it is made of limestone.

He also cited security concerns for rejecting the Egyptian request.

Secretary General of the Supreme Council of Antiquities Zahi Hawwas dismissed the director's fears, saying Egypt has offered the Germans all necessary guarantees and safety measures.

He also rejected reports that Egypt will not give back the masterpiece to Germany.

"Egyptians are not pirates," Hawwas said. "We live in the 21st century."

Hawwas threatened that if Berlin remained adamant, he would unveil proof that the bust had been stolen in Egypt and start legal action to restore it forever.