UPDATE 1-Airgas rejects Air Products' tender extension

* Air Products extends $60-per-share offer to June 4

* Air Products says 12,291 Airgas shares tendered

NEW YORK, April 1 (Reuters) - Airgas Inc (ARG.N) on Thursday repeated its view that a $5.1 billion hostile bid by Air Products (APD.N) "grossly undervalues" the company, after larger rival Air Products earlier extended its tender offer for Airgas.

Air Products said its $60-per-share offer to Airgas will now expire at midnight on June 4. As of Thursday, about 12,291 shares of Airgas stock had been tendered, according to the statement from Air Products.

The Air Products' offer, made in February, was originally due to expire on April 9.

Shares in Allentown, Pennsylvania-based Air Products closed down 8 cents at $73.87. Shares in Radnor, Pennsylvania-based Airgas closed up 34 cents at $63.96. (Reporting by Elinor Comlay; Editing by Gary Hill)