Anti-narcotics police in Nyali, Mombasa, early Friday morning arrested two Nigerian nationals with 1.5kg of heroin with a street value of Sh4.5 million.
Chukwu James and Gageche Gold Patience were arrested in a raid on their apartment in the posh estate.
Officers told the Nation that they found the suspects packing the drugs in readiness for a trip to Brussels, Belgium.
The drugs, the officers said, had been hidden in a suitcase.
Sources told the Nation that the narcotics had been sourced from neighbouring Tanzania.
The police are expected to issue a formal statement on the arrests later today.