Abstract: The invention relates to a papermaking agent composition, preferably in powder form, which comprises a water-soluble polymer, which comprises 21-30 mol-% of vinylamine units and has an average molecular weight of at least 1 000 000 Da. The invention relates also to a method for treating of fiber stock in manufacture of paper, board or the like, where a thick fiber stock is obtained, it is diluted to a thin fiber stock having a consistency <3% by addition of water, and the thin fiber stock is drained and a continuous fibrous web is formed. The papermaking agent composition is added to the thick fiber stock or to the thin fiber.

Abstract: The invention relates to a papermaking agent composition, preferably in powder form, which comprises a water-soluble polymer, which comprises 21-30 mol-% of vinylamine units and has an average molecular weight of at least 1 000 000 Da. The invention relates also to a method for treating of fibre stock in manufacture of paper, board or the like, where a thick fibre stock is obtained, it is diluted to a thin fibre stock having a consistency <3% by addition of water, and the thin fibre stock is drained and a continuous fibrous web is formed. The papermaking agent composition is added to the thick fibre stock or to the thin fibre.