Anti-censorship group Article 19 said the decision to support the trip in October by Birmingham Chamber of Commerce would offer succour to the country's military regime.
Each of the 27 British-based companies on the three-day mission will receive grants from the DTI. The firms are looking to reap lucrative oil and construction contracts.
John Lamb, spokesman for the Chamber, said: "With export opportunities as they are, our companies can't afford to turn their back on any country, no matter what its human rights situation."
News of the mission came as Labour and Liberal Democrat MPs signed a Commons motion calling on the suspension of all such contacts with Nigeria.
The African state remains suspended from the Commonwealth for its poor human rights record following the execution of dissident Ken Saro-Wiwa and other activists.
Although no UN trade sanctions have been enacted, the European Union has banned all relations with the Nigerian military and imposed an arms embargo and visa restrictions.
Foreign Secretary Robin Cook singled out Nigeria for condemnation when he first launched his ethical foreign policy last year and insisted that it should remain suspended from the Commonwealth.
However, a Foreign Office spokesman said: "In terms of international obligations, there is nothing that stands in the way of trade in Nigeria."
Frances D'Souza, executive director of Article 19, said that financial and political supporting for this trade mission to Nigeria made a mockery of Foreign Secretary's Robin Cook's ethical foreign policy.Reuse content