The candidates were caught browsing the internet on mobile phones to solve the papers, the News International reported Wednesday.
The openings were announced to fill 130 vacant positions, including 34 for officer-level posts, in the NACTA, the newspaper said.
There were around 10 invigilators for 5,000 candidates. Soon after the exam started, hundreds of candidates were found openly browsing the internet on their smart phones to answer the multiple choice questions and reading up on counter-terrorism.
The invigilators were also accused of favouring some candidates, the report said.
NACTA coordinator Hyder Ali admitted mismanagement during the exams. He also said mobile phones were used for browsing and question papers were delivered with delay to several candidates, the report said.
Ali said the intelligence agency officials turned out to be the trouble-makers as they started arguing with the invigilators when efforts were made to take away the mobile phones from the candidates.
“We later cancelled the papers of those found cheating,” News International quoted Ali as saying.