Sigma Pharmaceuticals Ltd, Australia's major drug manufacturer, says it has not been given any formal offer by Aspen Pharmacare of South Africa as of yet, as the latter intends to continue carry out due diligence.

A few weeks ago, Aspen made a non bonding, conditional, and indicative takeover offer to Sigma worth $707 million, valuing the Australian drug maker at 60 cents per share, and agreed to carry out due diligence.

Following then, Sigma has announced a profit warning that started speculations that Aspen might lessen its bid or withdraw it totally.

The extended exclusivity period of Aspen with Sigma promptly ended at business closing yesterday.

"Aspen has not made any formal proposal to Sigma and Sigma continues to recommend that shareholders take no action at this time," Sigma stated to the Australian Securities Exchange (ASX).

"Sigma is continuing the previously foreshadowed asset sale program and will consider other opportunities that may enable it to improve shareholder value."

In the previous month, Sigma said the effects of its generic arm performing poorly could cause the company to fail in meeting its budget.

The leading player in the Australian drug industry on generics, Sigma struggles with a worn out share price.

It has posted an annual loss, and its top three executives left their posts earlier in the year.