An investor coalition welcomes a new rule from the Securities and Exchange Commission that aims to halt human-rights abuses in the mining of four minerals in central Africa, but believes it doesn't go far enough.

"Although we are pleased this unprecedented rule has finally been issued and now has the potential to drive transparency and accountability in product supply chains, the rule falls short in the timing of implementation and depth of reporting," said Patricia Jurewicz, director of the Responsible Sourcing Network.

The group, which included sustainable, socially responsible and faith-based investors, made additional recommendations to the SEC prior to the release, several of which were included in the final rule. Copies of the recommendations to the SEC and a list of the 82 investor organizations that signed on to the letters are available at www.sourcingnetwork.org/sec.

The SEC rule on Section 1502, the "Conflict Minerals" provision, of the Dodd-Frank Act requires that U.S. manufacturers and companies that contract with them file reports starting in May 2014 identifying where they obtained any of four minerals associated with human-rights abuses in central Africa, Bloomberg News reported.

The rule requires companies to make reasonable efforts to trace sources of tin, tantalum, tungsten and gold in their products and to do a deeper search if the metals may have come from mines that have helped fund armed groups in the Democratic Republic of Congo, Bloomberg said. Metals certified as scrap or recycled would automatically be considered conflict-free under the SEC rule, it adds.

"Investors will benefit from this rule, since it promotes transparency at all levels of a company's operations. We see mandatory reporting to the SEC on raw material sourcing as a much needed step for highlighting risks in the most vulnerable area of a company's supply chain," said Lauren Compere, managing director at Boston Common Asset Management LLC.

Although the rule will eventually provide greater certainty and clarity for investors, giving companies two or four years (depending on size) to uncover where all of their "indeterminate" minerals come from is too long, especially when coupled with no requirement of an audit during this time, the investor group said. They also were disappointed mining companies are excluded from the reporting requirements.

"The final rule will give investors consistent disclosures that they deserve when making investment decisions," said Susan Baker, manager of social and environmental advocacy at Trillium Asset Management. "We've already seen some companies take meaningful steps to trace their supply chains, but due to the 'phase in' investors will have to press companies over the next four years for continuous and rapid improvement in addressing these human rights risks."