A drug trafficker from Ghana and his female courier from Zambia have been arrested in Singapore by officers who seized 20.6 kilogrammes of cannabis, the largest haul in years, officials said on Tuesday. If convicted, both face death by hanging under the city-state's tough drug laws, dpa reported. The seized cannabis has a street value of 410,000 Singapore dollars (269,000 US dollars). Officers trailed the 29-year-old Ghanaian from his hideout-cum-drugstore to a budget hotel on Monday, Channel NewsAsia reported. Soon afterwards, he left with a black bag. Officers who arrested him found 14 kilogrammes of cannabis in the bag. Another 6.6 kilogrammes were recovered from his rented room, the report said. A team raided the hotel and arrested the 21-year-old Zambian courier. She had come from Johannesburg, South Africa. A 21-year-old Nigerian and a 35-year-old stateless African were executed on January 25 for drug trafficking despite international calls for clemency. Iwuchukwu Amara Tochi of Nigeria and Okeke Nelson Malachy, 35, were convicted of trafficking in 727 grams of heroin. Amnesty International claims Singapore has the highest rate of executions per capita in the world.