NS&T yesterday heightened the bidding over Security National Bank by spending Security's shareholders a four-page clarification of its initial offer.

The clarification letter was in response to an Aug. 19 note sent by Secuirty's board of directors requesting that its shareholders reject NS&T's offer to buy up to 100 percent of Security's shares at $62 per share.

Security, Washington's eighth-largest bank, has resisted the larger bank's Aug. 4 offer. Security Chairman Robert K. Koontz Jr. and President Thomas J. Schaefer last week sent a letter to stockholders characterizing NS&T's offer as an attempt to draw stockholders from the security of solid profitability into the uncertain world of corporate finance. The letter also criticized the price and the substance of NS&T's offer.

But NS&T yesterday countered Security's letter with one of its own telling the stockholders that its $62 offer "is a very attractive price for your shares."

Security has said the $62 price was too low in light of its prospects for profitability. But NS&T said the ratio of the $62 offer to the June 30 book value is 170 percent, "nearly twice the average for the last five years."

The NS&T letter, signed by Chairman Joseph H. Riley, also said shareholders would be entitled to $62 plus the full 70-cents-per-share quarterly dividend voted by the Security board earlier this month.

In addition, if a shareholder wants to partake in a more attractive tender offer that may arise, NS&T said shareholders can withdraw their shares from the NS&T bid.

"With all the takeover news in the press, you may be reluctant to tender you shares now, thinking that someone else will make a better offer," the NS&T letter said. "If that happens you can withdraw you tendered shares at any time before we make payment to you."

Secutiry, to ward off the hostile takeover, announced last month that it would merge with the smaller Washington Bank. That announcement followed Security's rejection of a bid from James Madison Ltd., parent company for James Madison National Bank, to pay $60 a share for up to 44 percent of Security's stock.

But NS&T said yesterday the proposed merger with Washington Bank may not be as beneficial to shareholders as its own offer, NS&T said the merger would result in a 12.8 percent decrease in shareholders' ownership in Security Bank unless they also own Washington Bank Stock. NS&T also said while Security Bank ranked very high in its peer group of Washington banks, Washington Bank ranked the lowest in its group.

"What would the merger give you?" NS&T asked. "Nothing in hand, just the acquisition of a bank with one office and total assets less than those in you main office alone."