A spokeswoman for the SFO said that the inquiry concerned dealings about 18 months ago.
It is understood that the inquiry does not relate to the company's present activities, but to sub-underwriting arrangements at the time of its flotation.
The SFO's statement followed an announcement from Richmond Oil, which said that its own internal investigation had found no evidence of irregulatities 'on the part of the company or its directors'.
The internal review - carried out by David Webb, Richmond's company secretary - had also concluded that the company's own files disclosed no evidence of a 'circle of funds at the time of or following the flotation'.
The so-called circle refers to recent allegations of irregularities involving the channelling of up to pounds 16m via several offshore companies, giving the impression that Richmond's offer-for-sale was fully underwritten.
The company, chaired by Robert Fox, also said it had no knowledge of any inquiry into the company by the SFO, and that none of its directors or staff had been interviewed by the SFO.
'The board would be happy to co-operate with the SFO, were it to commence an inquiry,' it said.
Richmond joined the stock market in July 1989 via an offer for sale at 105p a share, valuing it at almost pounds 60m. The flotation was sponsored by Corporate Broking Services, the stockbroker which has since closed down.
The shares slumped to a low of 55p shortly after Richmond's debut because the issue had flopped. However, they moved up sharply in subsequent weeks before they began a long decline. They closed unchanged at 5.5p yesterday.Reuse content