The House of Representatives has ordered an immediate investigation into a multibillion dollar scheme used by the Nigerian National Petroleum Corporation NNPC, in connivance with Swiss oil dealers, to rip Nigeria of nearly $7 billion.

Ceoafrica gathered that the schemes, documented in a report titled Swiss Traders' Opaque Deals in Nigerian, released last week Monday by Swiss non-governmental advocacy organisation, the Berne Declaration, involved the NNPC teaming with major Swiss oil trading companies to drain Nigeria of revenue through the sale of crude oil below the market value.

The report details the various methods employed by Nigerian and foreign fuel importers, such as creating offshore subsidiaries referred to as "letterbox companies", ship-to-ship transfer to create untraceable paperwork, payment of subsidy money to phantom and non-existing importers, and partnering with politically exposed fraudsters to defraud the country over $6.8 billion from 2009 and 2011.

Berne Declaration describes the Nigerian oil scam as the greatest fraud Africa has ever known.

Prominent among the shady deals are the partnership between the NNPC and two Geneva-based commodity trading firms, Vitol and Trafigura, registered in Bermuda.

Through NNPC partnership with Vitol (the largest oil trader in Switzerland) and Trafigura (the third largest) described as 'operational and financial black boxes' billions of naira that should have accrued to the government are wired to Bermuda where the joint venture is established.

"In reality, the profit generated by these entities escapes State coffers, first, because no taxation in Bermuda is paid, since the tax on profits is zero," the report stated.

"Vitol and Trafigura alone took respectively 13.44 % and 13.49 % of Nigerian crude oil exports in 2011 for a cumulative value of 6.7 billion dollars."

The Nigerian House of Representatives on Tuesday stated that it was alarmed by the report, and would expect an investigation to be concluded within four weeks.

The House committees on petroleum (upstream), petroleum (downstream), and justice, are to carry out the probe and report to the House within the stated period.

The House is further worried about the numerous damaging allegations contained in the report against Nigerian National Petroleum Corporation (NNPC) and its subsidiaries accused of not publishing detailed financial reports since 2005.