The kidnappers who seized 19 hostages including European tourists in a remote desert area of Egypt have threatened to kill them if attempts are made to find them by plane, an Egyptian official said

The official, who spoke on condition of anonymity, said the kidnapped tour operator contacted his German wife and told her of the threat, which she reported to Egyptian authorities.

The masked kidnappers took the 19 people -- five Italians, five Germans, a Romanian and eight Egyptians -- while they were on an adventure safari in southwestern Egypt on Friday.

It was the first time foreign tourists had been kidnapped in Egypt and the case posed a new challenge to the security-conscious government in a country which depends on foreign tourism accounts for 6 percent of the national economy.

Islamic militants have hit the country's tourist industry in recent decades with bomb and gun attacks that have killed hundreds.

The official said Egyptian authorities had traced to Sudan calls from the kidnappers to the tour operator's German wife. The Egyptian state-owned daily newspaper Al-Ahram on Tuesday quoted Tourism Minister Zoheir Garrana as saying the hostages were all in good health, and that German authorities were in talks with the kidnappers over the ransom.

Security sources said on Monday the kidnappers were demanding 6 million euros ($8.8 million) to free the hostages, and said there was no sign militant Islamists were involved.

A security source said Egyptian authorities were also in talks with the kidnappers.

Egypt's foreign minister, Ahmed Aboul Gheit, said at the United Nations on Monday that the tourists had been freed and were safe and sound, but officials later denied that account.

Garrana told Egyptian television on Monday that the kidnappers were 'most likely' Sudanese.

The desert area where the borders of Egypt, Sudan and Libya meet is thinly policed and is close to chronic conflicts in Darfur in western Sudan and in eastern Chad.

Gilf Al-Kebir, where the tourists were heading, attracts adventure travellers with dramatic landscapes including a massive crater and the Cave of the Swimmers, whose prehistoric paintings won fame through the 1996 film 'The English Patient'. - Reuters