Scottish Football Association chief executive Stewart Regan has said Fifa now has the green light for radical reform after its president Sepp Blatter finally caved into demands for him to resign.

The Swiss footballing bureaucrat said he is leave his post following allegations that his key lieutenant, Jerome Valcke, was involved in making a huge payment to one of the arrested Fifa officials.

Hours later, in yet another twist to the on-going scandal, it emerged that US prosecutors have placed Blatter under investigation.

US officials told the New York Times they hoped to gain the assistance of several senior Fifa figures now under indictment on charges of racketeering and money laundering to try to build a case against Blatter.

In a statement at a press conference in Zurich, Fifa president Mr Blatter said: "An extraordinary congress is to be called to elect my successor as soon as possible."

He added: "Fifa's interest are dear to me. That's why I have taken this decision. What counts most for me, is the institution of Fifa and football around the world."

It came hours after it emerged US law enforcement agencies are probing an alleged $10m (£6.5m) payment Mr Valcke authorised from a Fifa official.

Mr Valcke, Fifa's secretary general, is allegedly the previously unidentified "high ranking Fifa official" who prosecutors in the case alleged made the huge payment in 2008.

It is claimed the sum came from accounts allegedly controlled by another Fifa official Jack Warner, a former vice president of FIFA and president of Concacaf football organisation.

Mr Warner was among a number of officials arrested by police las week.

 The claimed payment forms a major part of an indictment accusing Mr. Warner of taking a bribe in exchange for helping South Africa secure the right to host the 2010 World Cup.

SFA chief Mr Regan said: "The Scottish FA welcomes the news today that Sepp Blatter has confirmed his intention to step down as President of FIFA and convene an extraordinary Congress to elect a replacement.

"We, like many other national associations, have maintained that the governance of world football's governing body requires to be reformed - especially in light of recent allegations - and we are glad Mr Blatter now shares this view.

"We will discuss today's developments and any collective next steps with all other Uefa associations at next weekend's Champions League Final in Berlin."

The SNP Government's sports minister Jamie Hepburn also welcomed Blatter's resignation, adding that he and hoped it signalled a fresh start for Fifa. He added he hoped "a change of leadership will help Fifa to begin to recover its reputation and regain our confidence in the way the global game is run. "

Mr Hepburn added: "Recent arrests of senior Fifa officials on charges of alleged corruption are deeply concerning for anyone who cares about football. The World Cup is too important to be tarnished with scandal and suggestions of criminal behaviour. I support the calls of Stewart Regan for fundamental and urgent changes to the way Fifa is governed."

England FA chairman Greg Dyke welcomed the decision, but said questions must again he raised over the hosting of the 2018 World Cup in Russia, and the controversial decision to award the tournament to Qatar in 2022.

Mr Dyke said: "Something has come out of the events of last week that has caused Mr Blatter to resign … He's gone. At long last we can sort out Fifa. We can go back to looking at those two World Cups. If I were Qatar right now I wouldn't be feeling very comfortable."

The "belated" resignation of Blatter as Fifa's president is "only the beginning of the process of change we need to see", Culture Secretary John Whittingdale added.

Mr Whittingdale said: "Governments, national associations and international confederations, along with players and fans, have all called for Sepp Blatter to resign in recent days.


"We welcome his belated announcement today but this is only the beginning of the process of change we need to see from Fifa. I sincerely hope this is the first step to a new Fifa that can command the confidence and respect of the football world once again."

Fifa head of compliance and audit, Dominic Scala, said: "Fifa is determined to address the issues that are afflicting Fifa. We wany to fundamentally reform the way in which people see Fifa."

He added the election of a new president is likely to take place between December and March.