Belgore said the national honour cannot be given to dead people, adding that only soldiers can be given posthumous medals for their bravery.
The President had on Wednesday, June 6, awarded a posthumous award of the Grand Commander of the Federal Republic (GCFR) on Abiola, the presumed winner of the June 12, 1993 election.
Buhari also declared June 12 as the new Democracy Day instead of May 29, saying June 12 is a more symbolic day.
But Belgore, a retired judge, in an interview with Premium Times on Wednesday, said a national honour cannot be given to a dead person, "much less the GCFR", which is the highest honour in the land.
"It is not done… it is for people living", the retired judge was quoted as saying.
"The only thing they could do is to name a place after him, but national honours award, no."
Belgore, who chaired the 2016 national honours committee, says that under the 1963 National Honours Act, only soldiers or other servicemen can be awarded posthumous medals for their bravery.
According to him, Buhari did not consult him before taking the step.
The President also honoured Abiola's running mate in the 1993 election, Baba Gana Kingibe, and the late human rights lawyer, Gani Fawehinmi with the GCON title.
Buhari said the commemoration and investiture would take place on June 12, 2018.