Magindustries has broken a six-week silence on its Chinese approach by announcing "significant progress" on due diligence checks required before sealing the deal.
The Canadian fertilizer group, which revealed the bid in June, said it had held due diligence sessions with its Chinese bidder, whose identity has yet to be revealed, in Africa, Europe and North America.
And, with further meetings due in Beijing next week, Magindustries said it was extending the suitors' period of exclusive talks by a month to the end of August.
A successful tie-up would make Magindustries, which is developing a potash mine in the Republic of Congo, one of a list of resource groups to fall into Chinese hands this year.
The deal as outlined last June proposed the bidder, known to be a multinational, buying 400m new Magindustries shares at Can$0.70 apiece, equivalent to a 53% stake.
The suitor, which is also seeking power over the debt financing of the Congo Kouilou potash mine, which requires an overall injection of Can$835m, would gain the right to appoint a majority of MagIndustries directors.
Magindustries shares, which hit Can$0.78 after the approach was announced, stood at Can$0.485 in afternoon trade, down Can$0.025 on the day.