A new report from watchdog group Global Witness has identified a pattern of logging abuse across West and Central Africa in which permits designed to promote small businesses are being allocated by the hundreds to industrial companies.

The use of these "shadow permits" is undermining efforts to curb corruption in the timber sector and is increasing the likelihood that illegal wood is being exported to Europe and elsewhere, according to the report published Tuesday.

The report says permits intended to help small-scale enterprises are instead being used to circumvent commercial logging regulations in Ghana, Cameroon, Liberia and Congo.

The European Union Timber Regulation went into effect in March, prohibiting the import of illegal timber. But Global Witness said the continued use of shadow permits could render the measure ineffective.