The West African Examinations Council (WAEC) said it has cancelled 151 certificates already issued to candidates that sat for both school and private exams.
The exam body said they were later found to have engaged in examination malpractice.
Also, the council has taken possession of 29 certificates (both school and private candidates exam) returned by born again Christians who sought for restitution.
The National Examinations Committee (NEC) of WAEC took the decision recently at its 62nd meeting held in Lagos.
Among the cancelled certificates, include two issued 28 years ago (1989) and 27 years ago (1990) by WAEC while the ones issued in 2012 and 2013 are the current certificates.
A breakdown of the cancelled certificates showed that the highest number, 14, was issued in 2001 and 2002, 13 each in 1999 and 2000.
The statistics further revealed that WAEC cancelled 12 certificates in 2003, 10 in 2006, eight in 1988, seven each in 2004, 2007 and 2010, five each in 1993, 1995, 2009, 2012 and 2013. Others are four in 1994 and 2008, three each in 1996 and 2011, two each in 1997 and 2005 as well as one each in 1989, 1990 and 1992.