Sepp Blatter has announced he is to resign as president of FIFA.

The head of football's world governing body for 17 years, who was re-elected for a fifth term only last week, has called for an emergency FIFA congress to be held as soon as possible at which his successor will be elected.

Speaking at an unprecedented, emergency press conference, hastily organised after another day of allegations of corruption and bribery within his organisation, Blatter said: "I will organise an extraordinary congress for a replacement for me as president.

"I will not stand. I am now free from the constraints of an election. I felt compelled to stand for re-election, as I believed that this was the best thing for the organisation. That election is over but FIFA’s challenges are not and FIFA needs a profound overhaul.

"While I have a mandate from the membership of FIFA, I do not feel that I have a mandate from the entire world of football – the fans, the players, the clubs, the people who live, breathe and love football as much as we all do at FIFA. 

"Therefore, I have decided to lay down my mandate at an extraordinary elective congress and I will continue to exercise my functions as FIFA president until that election. The next ordinary FIFA Congress will take place on 13 May 2016 in Mexico City but this would create unnecessary delay and I will urge the executive committee to organise an extraordinary congress for the election of my successor at the earliest opportunity."

No timescale has yet been laid out for when this emergency congress will take place but Greg Dyke, chairman of the Football Association, said that Blatter's decision was "brilliant for world football".

Blatter outlined in a statement that he will implement a number of reforms before his successor is elected, and these will begin remarkable and widely called-for change to the structure of a discredited organisation.

"The election will need to be done in line with FIFA’s statutes and we must allow enough time for the best candidates to present themselves and to campaign. Since I shall not be a candidate, and am therefore now free from the constraints that elections inevitably impose, I shall be able to focus on driving far-reaching, fundamental reforms that transcend our previous efforts," Blatter said.

"For years, we have worked hard to put in place administrative reforms, but it is plain to me that while these must continue, they are not enough. The executive committee includes representatives of confederations over whom we have no control, but for whose actions FIFA is held responsible. We need deep-rooted structural change.

"The size of the executive committee must be reduced and its members should be elected through the FIFA congress. The integrity checks for all executive committee members must be organised centrally through FIFA and not through the confederations. We need term limits not only for the president but for all members of the executive committee.

"I have fought for these changes before and, as everyone knows, my efforts have been blocked. This time, I will succeed. I cannot do this alone. I have asked Domenico Scala to oversee the introduction and implementation of these and other measures.

"Mr. Scala is the Independent Chairman of our Audit and Compliance Committee elected by the FIFA Congress. He is also the Chairman of the ad hoc Electoral Committee and, as such, he will oversee the election of my successor. Mr. Scala enjoys the confidence of a wide range of constituents within and outside of FIFA and has all the knowledge and experience necessary to help tackle these major reforms.

"It is my deep care for FIFA and its interests, which I hold very dear, that has led me to take this decision. I would like to thank those who have always supported me in a constructive and loyal manner as President of FIFA and who have done so much for the game that we all love. What matters to me more than anything is that when all of this is over, football is the winner."