South Africa's Aspen Pharmacare Holdings Ltd has been confirmed as the surprise bidder for Sigma Pharmaceuticals Ltd.

In a statement, Sigma general counsel and company secretary Sue Morgan-Dethick said, "Sigma is now able to confirm that the party referred to in Sigma's announcement of 21 May 2010 is Aspen Pharmacare Holdings Limited."

Sigma Pharmaceuticals Ltd's board is considering the proposal and recommended that shareholders take no action at this stage.

Sigma said last week it had received a non-binding, indicative and conditional takeover proposal of $0.60 per share by way of a scheme of arrangement or other whole of business transaction but did not reveal the bidder.

The takeover offer came after Sigma chairman Dr. John Stocker announced his retirement following the company's annual general meeting on June 21. Non-executive director Doug Curlewis has also decided to leave the board after the meeting.

Last month, Sigma chief executive Elmo de Alwis resigned in the wake of criticism after the company reported a massive $389 million loss for the year to January 31, 2010. His resignation was followed by Sigma chief financial officer Mark Smith.

Sigma Pharmaceuticals Ltd is a leading Australian manufacturer and marketer of prescription, over-the-counter and generic pharmaceutical products.

Aspen Pharmacare Holdings Ltd is Africa's largest pharmaceutical manufacturer and a major supplier of branded and generic pharmaceuticals in approximately 100 countries.

Sigma shares closed on Friday at 48 cents.