LONDON - The campaign to succeed Sepp Blatter as FIFA chief turned bitter on Friday when a presidential candidate asked for an investigation into whether his main rival is trying to break election rules.

Prince Ali bin al-Hussein accused Sheikh Salman bin Ibrahim al Khalifa of a "blatant attempt to engineer a bloc vote" by signing a pact between the Asian Football Confederation he heads and its counterpart in Africa.

With 54 voters, Africa has the biggest say in the Feb. 26 presidential vote by FIFA's 209 federations. The four-year accord is between the AFC and the Confederation of African Football headed by Issa Hayatou, who is also acting FIFA president following Blatter's ban.

It will be up to FIFA election watchdog Domenico Scala, who chairs the audit and compliance committee plus the electoral committee, to decide whether there is anything wrong with the Africa-Asia deal being announced six weeks before the vote.

"I am concerned that there has been an attempt to breach electoral rules in the FIFA presidential election," Prince Ali, who is also Jordanian Football Association president, said in a statement. "I have written to the FIFA ad-hoc electoral committee informing them of my concerns and asking them to examine the matter."

The escalating public dispute between the presidential rivals — both members of Middle East royal families — is damaging for FIFA as it tries to make a fresh start after bribery and fraud scandals. Blatter was last month banned from the sport for eight years over an unethical payment to UEFA President Michel Platini.

Bahrain's Sheikh Salman, who is considered to the front-runner to replace Blatter, signed the co-operation agreement with Hayatou at an event in Rwanda on Friday ahead of the African Nations Championship. Described as a "re-launch" of existing mutual ties, the memorandum of understanding formalizes Asia and Africa helping each other on integrity, administration and coaching issues.

"I have always promoted cross-regional understanding, however the timing of this MoU between the AFC and the CAF looks like a blatant attempt to engineer a bloc vote," Prince Ali said. "Africa's proud football associations are not for sale and development resources belonging to national football associations should not be used by presidential candidates and confederation presidents for political expediency.

"Questions must be asked: was this deal approved by the members of the executive committees of both the AFC and CAF and is the timing of the announcement, prior to a presidential election, acceptable? Now more than ever, this apparent exploitation of confederation resources shows the world that the actions of individuals must stop bringing FIFA into disrepute."

There was no immediate response from Sheikh Salman's campaign. On the CAF website earlier Friday, Sheikh Salman said: "This is indeed a memorable day when our two great confederations come together in the spirit of friendship and co-operation."

Sheikh Salman and Prince Ali are competing against UEFA general secretary Gianni Infantino, former FIFA official Jerome Champagne and South African businessman Tokyo Sexwale in a five-man election field.

Prince Ali was beaten in May's presidential election by Blatter, who announced resignation plans the following week in the wake of criminal investigations into FIFA officials, and was later banished by the ethics judge. The prince served on FIFA's executive committee from 2011 until May 2015.

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