Some argue GM maize would help alleviate food shortages in Africa
A shipment of genetically modified (GM) maize has been blocked at the Kenyan port of Mombasa after protests by environmentalists.
The cargo came from South Africa - whose maize exports mainly go to Kenya - and contained maize varieties developed by US multinational Monsanto.
Protestors claimed that safety checks had not been carried out on the maize and that it could contaminate the soil.
GM imports have been banned in several African countries.
The 40,000-tonne shipment contained four varieties of maize, three of which were made by Monsanto.
Anne Maina, a spokeswoman for the Kenyan Biodiversity Coalition, told the BBC that the Kenyan government had not followed due process by carrying out safety checks on the imported maize.
The group also claimed Kenyan authorities had failed to tell the public of its decision to import the GM maize.
The shipment came from South Africa, the continent's biggest producer of maize, and was approved by that country's Department of Agriculture, Forestry and Fisheries.
Mariam Mayet, an activist at the South African-based African Centre for Biosafety, criticised her government's policy.
"The way it is, one is inclined to say that South Africa was a springboard to contaminate the rest of the African continent by allowing multinationals to export from South African soil," she told South Africa's Business Report newspaper.
Many African countries are under increasing pressure to grow GM crops to tackle hunger and malnutrition, and drought in recent years has caused food shortages in Kenya.