Police said the suspect arrested with 198 kilos of heroin in his possession in Chilaw on Thursday was believed to have transported 50 kilos of heroin on a previous occasion.
The suspect was being interrogated while a police team was searching his Dehiwela residence, a senior officer said.
Subsequently, the search yielded four million rupees.
An investigator said the suspect had received several overseas calls on his mobile phone and he had been overseas from time to time.
Police said the suspect had taken a detour on the day of his arrest but the police had received information that he would do so to avoid them.