MOMBASA - The US Drug Enforcement Agency (DEA) says it plans to re-open its office in Karachi to work with DEA agents in Nairobi and with Pakistani authorities.

To help control drug trafficking, Western law enforcement agencies are also stepping up operations in east Africa and countries closer to Afghanistan.

Most Europe-bound Afghan heroin still goes through the established ‘Balkan route’ via Iran and southeast Europe. But a spate of seizures along the Kenyan and Tanzanian coastline over the past few years points to a switch to a "southern route" via Africa.

Britain, which estimates it is the destination for about 20 percent of the heroin shipped through east Africa, has also stepped up its presence in the region.

One evening last November, a handful of policemen in Kenya's sweltering port city of Mombasa were handpicked to help in the final stages of a US-led drugs sting that spanned three continents.

The target was a mansion in the wealthy beach suburb of Nyali. The policemen were banned from using their mobile phones and the names of the men they wanted were kept from them until two hours before the raid. Secrecy was deemed vital in a region known for its corruption.

The quarry that night were the alleged leaders of the "Akasha organisation." The US Drug Enforcement Agency (DEA) had spent years infiltrating Akasha and alleges that the gang is part of a heroin supply chain that stretches from the poppy fields of Afghanistan through east Africa to the cities of Europe and the United States.

Police captured the alleged leader of the crime syndicate, Baktash Akasha, his brother Ibrahim, and two other men. Kenyan police charged them with trafficking narcotics to the US. Prosecutors in the United States subsequently indicted all four on charges including conspiracy to import heroin.

By 2014, when the DEA began the operation to catch the Akashas, Baktash had taken over the family business. A burly man with a receding hairline, he had built close links with major Pakistani heroin traffickers, the DEA alleges.

One such contact, the US indictment states, was Gulam Hussein, also known as the "Old Man." Hussein had lived on and off in Kenya since 2012. The indictment describes him as "the head of a transportation network that distributes massive quantities of narcotics throughout the Middle East and Africa."