Egyptian Bedouins seized two female American tourists and their Egyptian tour guide on Friday on the road to the historic monastery of St Catherine's in Sinai, security officials said.

A group of masked gunmen held up the tourists' bus in Wadi al-Soal in south Sinai, snatching the three before taking off, the officials said.

Bedouin sources told AFP the kidnappers were demanding the release of relatives held in Egyptian jails, without providing further details.

State television said a military airplane had been deployed over south Sinai, as a search operation quickly got underway.

The incident comes just days after Bedouins in north Sinai briefly seized 25 Chinese workers employed by a military owned cement factory, to demand the release of Islamist relatives detained over bombings in the peninsula between 2004 and 2006.