LEHIGH VALLEY, Pa. (AP) — Industrial gas supplier Air Products and Chemicals Inc. said Friday that it made an unsolicited cash bid of about $5.1 billion for smaller rival Airgas Inc. and is willing to make a hostile offer if necessary.

Airgas said its board will review the offer with financial and legal advisors and recommended that its stockholders not take any action yet.

But its shares climbed above the offered price in electronic trading ahead of the market opening, suggesting some traders expect the bid could go higher.

The offer, worth $60 a share, represents a 38 percent premium to Airgas' closing price of $43.53 on Thursday. Airgas shares rose $18.07, or 41.5 percent, to $61.60 in premarket trading.

A combination of the companies would create one of the biggest industrial gas companies in the world.

Air Products, which sells gasses including argon, nitrogen, hydrogen, helium and oxygen for industrial, medical and other uses, values the deal at approximately $7 billion, which includes $1.9 billion in debt. Like Air Products, Airgas also sells gasses. It also provides gas equipment, welding products, tools, safety gear and janitorial supplies.

Air Products previously made two written offers for its competitor, which were rebuffed. Airgas said it turned down those bids because it felt that they "grossly undervalued" the company and were not in its shareholders' or the company's best interests.

Chairman, President and CEO John McGlade said in a statement that the company told Airgas' board repeatedly that it was willing to raise its offer "to reflect any incremental value they can demonstrate."

Air Products, based in Allentown, Pa., said it will not be deterred if Airgas, based in Radnor, Pa., continues to turn down its bids.

"While it remains our strong desire to reach an agreement with Airgas on a friendly basis, we are fully committed to pursuing this transaction and are prepared to take all necessary steps to complete it, including making an offer directly to Airgas shareholders," McGlade said.

Air Products said it already has committed financing from J.P. Morgan to close the acquisition and is willing to make appropriate sales to contend with regulatory issues.

If the transaction goes through, Air Products anticipates it will immediately add to its earnings per share, excluding one-time costs.