"Maintaining safety and security of pilgrims requires us to take all the possibilities seriously. The kingdom of Saudi Arabia has witnessed in the recent past a fierce terrorist campaign, which does not exclude the holy sites," Prince Mohammed bin Naif bin Abdulaziz al-Saud, Saudi interior minister, told the Abu Dhabi daily The National Thursday.
He did not mention any specific threats. However, the newspaper noted from 2003 to 2006, the kingdom was targeted by al-Qaida.
The interior minister also called on pilgrims making the hajj to leave their political and sectarian differences aside.
"Hajj is not an area of political conflicts and sectarian differences," he said.
Saudi authorities estimate more than 2 million Muslim pilgrims from 100 countries will participate in this year's hajj, which starts Sunday and ends Oct.18.
Muslims are expected to make the pilgrimage to Islam's holiest city once in a lifetime.