Financial crime in the UK stemming from Nigeria involves "billions of pounds" but not enough is being done to stop it, a report has concluded.
Some scams promise millions of dollars in return for an up-front fee
Internet scams, credit card fraud and money laundering are going unchecked by governments in both countries, research group Chatham House says.
The crimes are not given priority but have become a "large and pressing problem", the author says.
Nigeria has become especially linked with "advance fee" or "419 scams".
This involves sending emails or faxes to potential victims around the world, offering a highly attractive but false financial deal.
Commonly the criminal says they need help in getting money out of the country with promises to share the rewards with the victim.
The criminal uses information they trick from the gullible victims and commonly strips their bank account.
These style of incidents alone cost the UK economy £150m a year - with the average victim losing £31,000 the report said.
Other examples of crimes included in the Chatham House report include more than £20m forged cheques and postal orders couriered from Nigeria's commercial capital Lagos being found in one day at Heathrow Airport.
In another incident, a handbag containing more than £1m worth of false cheques was found at a parcel centre in Coventry.
"Criminal activity is carried out by a small minority of Nigerians, relative to the size of the country and the number of nationals resident in Britain or visiting it," the report said.
"But the numbers of people involved are still significant and their successes reflect wider political and logistical shortcomings with the way the British authorities deal with financial crime."
Poverty in Nigeria had helped spark the growth of criminal networks, the report said.
But while the number of people involved was "vague", the sums of money were "significant" and "have almost certainly run into billions of pounds over the past 10 years", it added.
Nigerian passport holders deported for their role in scams often return to Britain and again get involved in the crimes, the research found.
Report author Michael Peel said action needed to be taken by both governments.
"The scale and scope of Nigeria-related financial crime highlights critical wider failures in the way the British authorities tackle fraud, corruption and money laundering," he said.
"Despite important, but limited reforms, criminal networks and corporate bribery still flourish.
"This raises questions about how sincere the governments in both countries are in their talk of change, particularly when significant political, commercial or energy interests are at stake."
The report urged Britain to set up a way of co-ordinating reports of Nigeria-related fraud.
It also called on law enforcement agencies and the Financial Services Authority to build better links with counterparts in Nigeria to cooperate in fraud and corruption cases.