Saudi Arabia says it has mobilized more than 50,000 police and troops to maintain security during this year's pilgrimage or Hajj to Mecca, which begins Tuesday.
Authorities say more than 1.5 million Muslims from 160 nations are already in the kingdom and will be joined by a half-million Saudi pilgrims. Many foreigners visited holy sites Sunday in the cities of Medina and Mecca.
Saudi Interior Minister Prince Nayef said security forces are focused on crowd control and the threat of terrorism.
He said the kingdom will do everything possible to prevent militants from using the five-day pilgrimage as a staging area for crossing into neighboring Iraq.
The Hajj is a requirement of all able-bodied Muslims at least once in a lifetime.
Some information for this report provided by Reuters and AP.