OSLO, June 12 (Reuters) - Swiss industrial group Georg Fischer said on Monday it had launched a rival cash bid for Finnish plumbing and heating systems maker Uponor , offering a premium of 12% compared to a bid by Belgium's Aliaxis.

Uponor's board, which had rejected the Aliaxis offer, said in a statement it recommended that shareholders accept the Swiss company's bid.

Georg Fischer's offer of 28.85 euros per share valued Uponor at 2.1 billion euros ($2.26 billion), which was at a 12% premium to Aliaxis 25.75 euro bid.

Uponor last month said the unsolicited offer from the Belgian group had drawn the attention of other potential bidders, but did not name any suitors at the time. ($1 = 0.9308 euros) (Reporting by Terje Solsvik; Editing by Jacqueline Wong and Rashmi Aich)