Restorers are at work on King Tutankhamun's beard, Egypt's state-run news agency MENA said.
According to the report, the restoration began on Saturday and is being carried out by a German-Egyptian team of restorers led by specialist Christian Eckmann.
"Tutankhamun's mask has been transferred from its exhibition hall to another room in the museum that has been turned into a restoration laboratory," antiquities department spokeswoman Mushira Mussa told Middle East online.
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The intervention takes place more than a year after the long, narrow, blue and gold beard suffered a botched repair.
Braided like a pigtail with the end jutting forward, the beard was unintentionally severed from the chin in August 2014 by workers adjusting the lighting in the case holding the priceless artifact.
Panicked curators did further damage by hastily gluing the beard back onto the fragile 3,300-year-old mask with fast-drying epoxy normally used for wood or metal.
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Moreover, the glue was used abundantly, causing it to flow along the beard and chin.
News about the botched repair broke in January, followed by a press conference by Egypt's antiquities ministry. At the news conference German restorer Christian Eckmann told reporters that the mask can be properly restored after the glue is removed.
One of the top attractions at the museum, the mask is made of gold and inlaid with stone, faience and glass. It was placed over the boy king's face after his death around 1323 B.C. at the age of 19.
The beard was loose when British archaeologist Howard Carter discovered King Tut's treasure-packed tomb in 1922 in Egypt's Valley of the Kings. It was re-affixed with adhesive in 1941.
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According to Eckmann, the glue likely loosened over the decades, leading to the accident last summer.
It is not yet known when the mask will be returned to its display case at the museum.
"It is a delicate operation. It has to be done very carefully," Eckmann said in January.