The Securities Investors Association Singapore (Sias) has challenged GMG Global to address shareholder concerns around a potentially unfair acquisition offer.

Halcyon Agri Corporation proposed last month to acquire the rubber plantation operator in a two-part deal. Halcyon will first seek to acquire the 51.12 per cent stake of GMG controlled by Sinochem International for $210 million.

The other 48 per cent or so will be acquired from minority shareholders through a proposed share swap that values GMG at 70 cents a share and Halcyon at 75 cents a share.

In a statement released yesterday, Sias questioned the rationale behind these valuations, given that GMG's net asset value was 93.42 cents a share as at the end of 2015, over three times that of Halcyon at 29.84 cents a share, according to their respective annual reports.

There is also not enough clarity on how the proposed $210 million offer to Sinochem was arrived at, Sias added.

"Does the board not think GMG is relatively under-valued in this instance? Does the board not think the offer to GMG shareholders is unfair?" Sias asked in the statement.

These questions were put to GMG independent directors Ong Kian Min and Tay Puan Siong in a meeting with Sias yesterday.

In response, the independent directors said the offer will be subjected to further review and approval.

"The independent directors of GMG informed Sias that the current offer is a proposal only and the board would be appointing an independent financial adviser (IFA). Nevertheless, the deal would require regulatory approval. Further, the minority shareholders of GMG will have the opportunity to vote on the proposal in due course."

GMG shareholders should not make rash decisions until more information on the matter is provided, Sias advised.

"Sias urged the GMG board to address the concerns of the minority shareholders at (today's) annual general meeting. We recommend shareholders to wait for the IFA report before making any decision regarding their shares."