Johannesburg - Mozambican police have seized 600kg of heroin, one of their biggest ever drugs hauls, hidden in a flat-bed truck they believe was heading from Kenya to South Africa, newspapers said on Thursday.

Two Guineans arrested told police on the northern border with Tanzania that the narcotics were fertiliser they were transporting on behalf of a Congolese national living in Nairobi, the Noticias newspaper said.

They unsuccessfully tried to bribe officers with $60 000, the paper added.

“The disproportionate height of the truck bed, the strange scent and the fact that the truck was apparently travelling with no cargo raised the police's suspicions,” police spokeswoman Malva Brito was quoted as saying.

With its porous borders, loose bank regulations and strategic location on Africa's east coast, Mozambique has become a trafficking hub for South American and East Asian drugs headed for Europe and South Africa. - Reuters