Egypt is still negotiating for the release of 11 kidnapped foreign tourists, despite an announcement they had been freed along with eight Egyptians.
A group of 19 people were taken hostage at gunpoint near the Sudanese border.
The group was on a desert safari in a remote corner of southwestern Egypt when they were taken.
The kidnapping is thought to be the first of foreign tourists in Egypt in living memory, although militants have hit the country's tourist industry in recent decades through bomb and shooting attacks that have killed hundreds.
Tourism Minister Zoheir Garrana said that masked men had taken the hostages who he identified as five Italians, five Germans, one Romanian and four Egyptians.
He said talks were under way on a ransom to release the hostages, which Egyptian state television said included an Egyptian border guard officer.
Egyptian security sources said the tourists were last seen on Sunday evening in Aswan, whose pharaonic sites are a popular tourist draw. They said they had been due to take part in a desert car and motorcycle rally.
It was not immediately clear if the tourists were taken on Sunday or Monday, security sources said. Based on monitored telephone communications, the group of tourists could have been moved over the border to Sudan, they added.
Italy's foreign ministry confirmed that five Italians were kidnapped. It said it was in contact with other countries involved, but gave no further details.
Attacks targeting tourists in Egypt's Nile Valley have been rare in recent years, although a series of bombings targeted tourists in resorts in the Sinai Peninsula between 2004 and 2006.
