Engine, which owns about 1% of Univar, said in an open letter that the bid by Brenntag confirms its view that the company is "undervalued" and a "highly attractive acquisition target".

While Brenntag and Univar did not disclose any financial details from their talks, Engine said a sale price between $38 and $44 per share is achievable if the Univar board runs a competitive sale process.

It urged the company to publicly invite more bids to begin the sale process.

(Reporting by Ruhi Soni in Bengaluru; Editing by Devika Syamnath)