NAIROBI (Reuters) - African law enforcement agencies should work closer together to stop the heroin and other hard drugs passing through their territories, a senior U.N. official said.

African governments seized just 1 percent of the 658 tonnes of opium, 91 tonnes of heroin and 65 tonnes of morphine confiscated globally in 2016, Amado de Andrés, from the United Nations Office on Drugs and Crime (UNODC) said.

“The problem is that there are not enough seizures in Eastern and Southern Africa. And there are not enough seizures in West and Central Africa,” de Andrés said at the launch of the World Drug Report 2018 in Nairobi on Tuesday.

Without tougher action, he added, there was a risk that trafficking networks in the south and east of the continent could start cooperating.

“That’s the problem we’re going to be seeing in 2019 and 2020. The links between these two networks, which are not happening yet, will happen,” said de Andrés, the agency’s eastern African representative.