At least four people have been killed in an explosion on a tourist bus in Egypt's Sinai region near the Israeli border, reports have said.

Israeli police told Reuters news agency that they heard an explosion from the Egyptian side of the Taba border crossing on Sunday. 

Three South Korean tourists and the Egyptian driver were killed while at least 13 tourists were wounded, Health ministry spokesman Ahmed Kamel told AFP news agency.

The interior ministry said in a statement the tourists had set off from Cairo and were waiting at the crossing to enter Israel when the explosion took place.

Officials told Al Jazeera that the bus was carrying 32 South Korean tourists and had arrived at Taba from the ancient Greek Orthodox St Catherine's monastery in central Sinai. The bomb went off during a drop-off at a Hilton hotel.

Jean Antoine of Craft Tours, the company which owns the bus, told Al Jazeera that the bomb was planted under the driver's seat inside the bus. He added that the bus was parked outside the monastery the previous night.

An Israeli police spokesman said that the bus was on its way to Israel. The victims will be treated in Egyptian hospitals, but Israel has dispatched medical teams to the border.

Al Jazeera's Nick Shifrin, reporting from Jerusalem, said that the attacks were a major turning point for the armed groups operating in Sinai.

Taba is a Red Sea resort area popular with Israeli and other foreign tourists. The area has been the scene of attacks before, most notably in 2004 when the Taba Hilton hotel was bombed, leaving 34 people dead - mostly Egyptians and Israelis.

Sinai has been rocked by several attacks since the removal of Islamist president Mohammed Morsi last July. Groups have also claimed to have carried out attacks in Cairo and other cities.

Source: Al Jazeera and agencies