Sigma Pharmaceuticals said on Monday that it has been offered to closely coordinate with US drug manufacturer Aspen Pharmacare in order to fetch a much promising bid for the company, though it confirmed that Aspen's exclusivity period has lapsed and no extensions have been made so far.

Sigma said that it has informed its American suitor that the company was "willing to continue working with Aspen to assist it to improve the proposal for Sigma shareholders, which could lead to the removal of conditions on Aspen's offer.

Aspen has earlier dangled an offer of 55 cents per share on Sigma after the company has completed its period of exclusive diligence as it clarified that closely coordinating with Aspen was not an indication that it would endorse Aspen's bid to the company's shareholders.

At this point, Sigma said that it is maintaining its earlier position that company shareholders should not take action on Aspen's bid as it added that "Aspen has also been advised that such discussions should not be interpreted as a willingness on the part of the board to recommend to Sigma shareholders an offer of $0.55 per share."

For now, Sigma said that it is continuing its considerations for the best business and financial structures that would push the company forward, which include some possible asset sales.

Sigma specified that "these considerations include evaluating expressions of interest for parts of the Group including Sigma's generics business," at stressed that the company has yet to arrive at final decision at this time.

Sigma stocks were trading at 45 cents on Monday's market opening.