Filipe Dju sat on the tangled roots of a mangrove tree in Quinhamel, Guinea-Bissau, a padlocked chain around his ankle tethering him to four other recovering cocaine addicts.

Three months ago, Dju’s family brought him to this tiny, swampy West African country’s first drug rehabilitation centre because he had turned violent using a drug barely seen here until 2005.

Guinea-Bissau, one of the world’s poorest nations, has become a major transshipment hub and the epicentre in Africa for the cocaine trade, said officials from the United States, Europe and the United Nations.

The shift demonstrates how the flow of drugs adapts not only to law enforcement pressure but also to the forces of global economics.

Officials said some of the world’s richest criminal gangs are exploiting barely functioning countries such as Guinea-Bissau, which has 63 federal police officers, no prison and a population that still lives largely in thatched-roof homes on dirt roads with no electricity or running water.

“West Africa is under attack,” said Antonio Maria Costa, executive director of the UN Office on Drugs and Crime, who recently visited Guinea-Bissau and concluded that it is so overrun by the cocaine trade that it could soon become Africa’s first “narco-state”.

Colombian cartels are responding to pressure for cocaine in nations such as Britain, Spain and Italy, where demand is soaring as the US market has levelled off, officials said.

Costa described the strong currencies in Europe, where cocaine sells for twice as much as in the US, as “a magnet” for the cartels.

Police raids in Colombia are increasingly turning up suitcases full of euros instead of the traditional dollars.

Government officials said drug smugglers bribing local people with small amounts of cocaine are creating addicts in a nation that never had them.

They said the drug trade has led to rampant corruption at high levels of government, threatening the economic and political stability of a country that endured a civil war as recently as the late 1990s.

The UN Development Programme ranks Guinea-Bissau 175th out of 177 nations on its Human Development Index.

The UN drug and crime office has noted that the national budget of Guinea-Bissau is roughly equal to the wholesale value in Europe of two-and-a-half tonnes of cocaine.

The country is best-known for its cashews and mangoes but its main attractions for the cartels are its weak government and coastal waters dotted with scores of uninhabited islands.

Officials said the drug traffickers don’t export directly to Europe because European navies and air forces would detect large shipments.

So they send ships and planes loaded with cocaine to West Africa.

Some is unloaded at abandoned airstrips in the islands off Guinea-Bissau; more is dropped at sea and picked up by small boats.

The cocaine is then broken up into still smaller loads and sent on to Europe in light aircraft or by human mules.

In 2006, Dutch police discovered on a single flight to Amsterdam 32 people travelling from Guinea-Bissau with hidden cocaine.

Guinea-Bissau’s navy has only two boats, one of which is out of service, and the air force has no working aircraft or helicopters.

“We have no military means over here. Nothing. Zero,” said Jorge Sambu, a top aide to the navy chief of staff.

So Lucinda Barbosa, chief of the judicial police in the former Portuguese colony, is making an attempt to fight the sophisticated cartels from her primitive downtown office, with 63 officers, only half of whom have guns.

The department has no handcuffs. It has one laptop computer, sporadic electricity and hole-in-the-ground toilets.

In the courtyard during a recent visit, a few barefoot officers lolled in the shade next to the smashed remains of several old computers.

“This is the most dangerous thing we have ever seen,” Barbosa said. “It’s really worrisome. They have guns, bullets and military equipment.”

Last August, Barbosa said, two Colombian men living in Bissau, the crumbling capital city, were caught with the equivalent of $150,000, two grenades, a handgun, an AK-47 rifle, pepper spray, military weapons manuals, more than 100 rounds of ammunition and maps of the country’s remote areas.

Barbosa said one of the Colombians had served five years in prison in Miami on a drug-related conviction.

But both suspects were eventually released by a judge, with no explanation, and they still live in Bissau, she said.

“The traffickers have found a paradise here,” said Constantino Correia, a top Justice Ministry official who is coordinating the government’s efforts against the drug traffickers.

Portugal and a handful of other countries, the European Union and the United Nations have pledged more than $6 million to help overhaul the justice system, Correia said, adding that the problems would take much more to fix.

Correia also said, with a deep sigh and his hand to his forehead, that even if Guinea-Bissau does manage to capture a big drug trafficker, it lacks a real prison in which to hold him. “We need a new prison. It’s urgent,” Correia said.