The Competition Commission wants the Constitutional Court to clarify the competition body's powers to investigate allegations of anti-competitive behaviour submitted by third parties.

The commission filed an application on Thursday for direct access to the Constitutional Court to appeal a decision of the Competition Appeal Court, it said in a statement on Monday.

The Competition Appeal Court's decision related to allegations of a cartel in the fertiliser industry involving Yara SA, Omnia Fertiliser and Sasol Chemical Industries.

Sasol settled with the Competition Commission with an administrative penalty amounting to R250-million in 2009.

Following this settlement, the commission wanted to amend its complaint against Omnia and Yara by introducing information apparently obtained from Sasol. Omnia and Yara challenged the commission's investigation.

The Competition Appeal Court found the referral against the two companies was invalid because the complainant did not intend to complain about the anti-competitive behaviour uncovered in the investigation.

"The purpose of the appeal is to seek clarity from the Constitutional Court on the proper scope and ambit of the commission's powers to investigate and refer complaints of anti-competitive behaviour submitted by third parties," the commission said.

Due to the precedent set by the Competition Appeal Court, the commission had to drop a case against SA Breweries due to lack of jurisdiction.