In charge of world football's governing body since 1998, Blatter, 79, said last year he was standing down amid a growing corruption crisis.

Five candidates want to replace him.

They are Sheikh Salman bin Ebrahim al-Khalifa, Gianni Infantino, Prince Ali bin al-Hussein, Tokyo Sexwale and Jerome Champagne.

The election process is expected to begin at 12:00 GMT, but several rounds of voting may be required before a winner is known.

Given everything that has happened to Fifa, this is seen as a pivotal moment for an organisation which has been heavily criticised for its lack of transparency and for failing to clamp down on corruption within it.

A new leader, together with a raft of reform measures, is seen as a chance to start afresh.

Acting president Issa Hayatou said Friday can "signal a new dawn", adding: "This is our opportunity to show we are united in building a stronger Fifa."

There have been widespread allegations of corruption, the arrest of leading officials, the banning of its president and the sight of big-name sponsors deserting the organisation.

Numerous Fifa officials have been indicted in the United States, while Swiss authorities are also investigating the organisation.

Blatter has also been banned from all football activity for six years after being found guilty of breaching Fifa's ethics rules over a $2m (£1.3m) "disloyal payment" to the head of European football's governing body Uefa, Michel Platini, who had been favourite to succeed the Swiss.

Former France captain Platini was also suspended. Both men deny any wrongdoing and are appealing to the Court of Arbitration for Sport.

Furthermore, Jerome Valcke, Fifa's secretary general and formerly Blatter's right-hand man, was banned for 12 years following allegations - which he denies - of misconduct while in office.Fifa's leader is the figurehead for world football, often seen in public alongside presidents, prime ministers and royalty.

There have been eight of them so far, presiding over the organisation's executive committee, which is where the real decision-making power lies.

Fifa organises World Cups and other international tournaments, distributes broadcasting rights and should both protect and develop the world's most popular sport.

The president also "legally represents" the organisation, "maintains relations between Fifa and the confederations, members, political bodies and international organisations", and "implements the decisions passed by the congress and the executive committee".

(BBC)