Citicorp Inc., which operates the Maryland-based CHOICE credit card company, said yesterday that it would open a bank in Maryland if the General Assembly approves a deregulation measure pending in the Senate.

The news that an out-of-state bank might move here immediately raised the stakes for passage of the bill, which the Senate will vote on this week.

In a letter delivered to Gov. Hughes and top legislative leaders, Citicorp President Ronald E. Geesey said "there is no doubt" that Citicorp would apply "immediately" for a bank charter in Maryland if the bill is approved.

The Citicorp letter was written at the request of Sen. John A. Cade (R-Anne Arundel), the minority leader, who had raised doubts about a key portion of the bill that would allow financial and retail institutions to charge annual membership fees for credit cards. CHOICE has lobbied intensively for the fee, saying the company could not compete effectively without it.

With 700 employes at its headquarters in Towson, CHOICE has been a key player in the wrangling over the banking bill. After Maryland's four biggest banks moved their credit-card operations to Delaware last year to take advantage of less stringent banking laws there, it was feared here that CHOICE would do the same if legislation were not passed.

Under Maryland law, Citicorp could open a bank in the state as long as it employed a minimum of 100 people, did not advertise, and remained in one location only.

Geesey said Citicorp would like to have a bank in Maryland because unlike Delaware, it has better access to two large cities, Baltimore and Washington, and a port.

"Even the phones work better in Maryland," Geesey said yesterday.