Dietrich Wildung, head of the Egyptian Museum in Berlin, contends the bust of Sun King Akhenaten's wife is too fragile to endure such a trip for the 2012 opening.
"Nefertiti is not a pop star that can simply go on tour," he said.
But Zahi Hawass, secretary-general of the Supreme Council of Antiquities in Egypt, vowed that if a pending formal request from the new Grand Egyptian Museum to exhibit the sculpture for three months is denied, all cooperation with Germany will end, The Times of London reported Thursday.
"We will make the lives of these museums miserable," said Hawass. "It will be a scientific war."
The 3,400-year-old bust was unearthed in the Egyptian desert by the archaeologist Ludwig Borchardt in 1912 and smuggled to Germany where it became a central part of Berlin's museum collection.
Wildung said the validity of its German ownership is not in doubt.
"She was donated to the state museum in 1920 by James Simon (who sponsored the dig)," he said.