Around 2.5 million Muslims have arrived in Mecca for the hajj, the annual pilgrimage to Saudi Arabia's holy sites. This year's pilgrimage has been overshadowed by the outbreak of pandemic influenza A (H1N1).

As part of efforts to prevent a massive outbreak of pandemic influenza, Saudi authorities have only issued visas to people who can prove they have been vaccinated against aid (H1N1). More than 100,000 security personnel and 20,000 medical staff are on hand and the authorities have reserved additional hospital beds for flu victims victims. Despite the precautions, 67 people have been diagnosed with the disease and four have died. The situation could be exacerbated by unusually wet and cold weather in Saudi Arabia.
 

The hajj begins with the tawaf; seven circuits of the cube-shaped Ka'bah building in the centre of the Mecca's Grand Mosque, After kissing the corner of the Ka'bah, pilgrims drink from the Zamzam well, then go to Mina where they spend the night before climbing the 70-metre hill called Mount Arafat. The hajj ends with the ritual stoning of the devil and is followed by a three-day festival called Eid.
 

The hajj is the fifth pillar of Islam and every able-bodied Muslim who can afford it, is obliged to undertake the hajj at least once in their lifetime.