Russian fertilizer maker Acron has offered 1.5 billion zlotys ($441 million) to buy up to 66% of Polish chemicals company Azoty Tarnow and expand its presence in the European Union.

Tarnow chief executive Jerzy Marciniak said Acron's offer was "rather low", while pension fund Aviva PTE, which owns around 9% of Tarnow, said it was "exceptionally unsatisfying".

"From our talks with shareholders we got the impression that they could only respond to the call with a price above 40 zlotys per share," Marciniak also told Polish TVN CNBC channel.

Poland is Tarnow's largest shareholder with a 32% stake. Deputy treasury minister Pawel Tamborski said: "The treasury will analyse Acron's offer ... not through its current market price, but with a wider horizon. It is about the expected positive effects of consolidation started by Azoty last year, as well as its results in the first and future quarters."

At a news conference in Warsaw, Acron deputy chief Vladimir Kantor said a higher bid would be unjustified. "Of course 2011 was a good year, but the forecasts for 2012 and forward are not that optimistic."

Tarnow itself expects 2012 net profit to fall from last year's 499 million zlotys on sales of 5.3 billion zlotys.

Acron, one of Europe's 10 largest mineral fertilizer groups with assets in Canada, China, Estonia and Russia, said it would grow Tarnow's business and use it as a base for operations within the EU, while also increasing its global sales network.

Acron's key production facilities are three plants that produce 1.7 million tons of ammonia per year as well as nitrogen, complex mineral fertilizers and other products.

It made a 2011 net profit of 20.3 billion roubles ($663 million) on sales of 65.4 billion.

"We are convinced that Azoty Tarnow's potential, in alignment with our global experience, major resource base and wide logistics network, will allow the companies to be competitive and will bring considerable benefits," Kantor said.

Tarnow shareholders will be able to tender their stock to Acron from June 6-22.