He was addressing the national ceremony at Ananda Srastalaya in Kotte to distribute school textbooks for 2017.
The minister charged that certain past pupils associations have aided in these illegal admissions, in return for monetary gains at some instances.
Reports continue to receive about admissions to grade one through illegal means despite the issuance of many circulars detailing the due procedure, said Kariyawasam.
In admissions for Royal College, Colombo even the addresses of foreign diplomatic missions have been given as places of residence, he said.
Education ministry secretary Sunil Hettiarachchi says admissions have been suspended to Royal College and several other popular schools pending complaints lodged by the Ceylon Teachers Union.
According to minister Kariyawasam, Royal College will resume the admissions on January 16.
More than 350,000 children across the country are being admitted to grade one from January 11.