Tourists to Egypt have been put on alert. “International tourism companies have urged holiday-makers in Egypt to remain in their hotels if they are already in the northern Sinai region of the country,” reports Al Arabiya.

The Sinai-based Islamist militant group Ansar Bayt al-Maqdis, or Supporters of Jerusalem, claimed responsibility for the bombing of a tourist bus recently in the Sinai. They also threatened more attacks.

“We didn’t get any new reservations in the past three days from our usual companies,” even though “it’s supposed to be the high season for tourism in Egypt,” Raymond Heshmat, reservation supervisor at the Taba Heights resort, told Al Arabiya News.

There has already been a drop in tourists. According to Heba Atteya, a senior tour operator in Cairo at NTS group, “An important drop was noticed in our reservations,” following the bus bombing in the resort town of Taba.

“Approximately 30 percent of tourists from outside Egypt have canceled their bookings in Sharm el-Sheikh and Dahab,” she said.

More than $1 billion in tourism revenue have been lost since the ouster of Islamist President Mohammad Mursi, Reuters reported.