According to a statement by the spokesperson of his campaign, Olawale Rasheed, Senator Adeleke also informed the missions of a clampdown on his supporters ahead of Thursday’s supplementary election.
Rasheed said the letter was sent to the European Union, the United States embassy and several diplomatic missions in Nigeria and the United Nations.
In the letter, Senator Adeleke criticised the Independent National Electoral Commission’s (INEC) for declining to declare him the winner of the governorship election.
The letter read in part, “I am constrained to write this letter to you, our diplomatic partners and friends of despotic happenings in Osun governorship polls which I won but for which I was not declared the winner.
“My life is under threat and leaders of my party are under siege before and after Saturday main polls.
“During the campaigns, we were subjected to countless attacks, I escaped about four assassination attempts.
“Our campaign vehicles were severally attacked, and our rallies disrupted. We went through the pre-election process under constant onslaught from political thugs and merchants of violence.
“Despite the violence-prone climate, I still won the election on live television, our votes were removed and protests for re-addition of the votes were rejected.
“After all the manipulations which saw about 4,000 votes removed from my total votes, I still won by close to 400 votes.”
Adeleke faulted the reason given by INEC for declaring the election inconclusive, insisting that he met constitutional requirement to be returned as the winner.
“In a brazen assault on democracy, the returning officer in open breach of the constitution refused to declare me the winner even after fulfilling constitutional stipulations,” he said.
“The officer erroneously justified declaration of the election as inconclusive based on violence in seven out of about 3,000 voting units across the state. It was a travesty of justice that is under challenge in court of law.”
The PDP candidate called on the international community to intervene and ensure the votes count.
He said, “We count on you to mount pressure on the ruling party to restore people’s mandate in Osun State.
“We make this request because Osun state is the cradle of Yoruba people, denying them their inalienable right to pick their governor is a potent threat to democratic sustainability in Nigeria.
“Our nascent democracy has been under intense pressure and it is not in our collective interest to deepen the national stress index.
“We seek your intervention to prevent another rigging underway in Osun state. I am the holder of the sacred mandate of Osun people. We need the international community to assist Nigeria to make votes count.”