A key House of Delegates committee gave quick and resounding approval today to legislation that would allow the giant bank Citicorp to expand into Maryland, but the full House later delayed its vote to enact the measure until the last hectic hours of the 1985 General Assembly on Monday.

Delays in printing final versions of the so-called "Citicorp bill" and a companion regional banking bill combined with the House's own leisurely pace to frustrate Gov. Harry Hughes' appeal for final passage of the two measures today.

"Time is running out," Hughes said in an interview after meeting with House Speaker Benjamin L. Cardin (D-Baltimore) to press for the bills.

If enacted, the Citicorp bill would carry out Hughes' agreement with the giant New York bank holding company under which the conglomerate would establish a credit card service center near Hagerstown in return for broader banking powers in Maryland.

Maryland bankers, who fear competition from Citicorp, received another setback today in their intense effort to kill the agreement.

The House Economic Matters Committee voted 20 to 2 to approve the Citicorp bill as amended by the Senate two days ago. A key amendment would restrict Citicorp or other banks that promise to create at least 1,000 new jobs to 20 branch offices in the first two years of operation in Maryland.

On a 21-to-1 vote, the House committee also accepted a companion measure that would establish two years of regional banking between Maryland, three other states and the District of Columbia. In 1987, the region would be expanded to include 11 new states, including Pennsylvania, home to several giant banks.

The committee votes were significant because they left the two bills in the form approved by the Senate. When it voted on the bills earlier this year, the House committee favored no limit on Citicorp's branches and wanted to allow full national banking starting in 1989.

If the full House approves the two measures without adding amendments requiring Senate approval, they would go immediately to Hughes for his signature.

Economic Matters Chairman Frederick C. Rummage (D-Prince George's) said he expects a few remaining House opponents to offer amendments on Monday in hopes of fatally snarling the bill on the final day of the legislature. "But we can stave them off," Rummage said.

Cardin, too, was confident about quick House action on the bills. "There is absolutely no problem in time," he said. "I don't see anything that could jeopardize the orderly conclusion on key issues" such as the banking legislation.

In delaying action on the banking legislation and several other big-ticket items until the final day, the legislature has left itself with a far more ambitious agenda for the closing hours than in recent years.

Also unresolved are bills to ban phosphate detergents in Mary- land -- which a conference committee will take up Monday morning to reconcile differences between the House and Senate -- and Hughes' package of legislation to further regulate and control health care costs.

House and Senate leaders met sporadically and unsuccessfully all day today to resolve the one outstanding issue in the health care package -- how the state will regulate the purchase of expensive equipment by doctors.

A compromise solution fell apart when Hughes objected to setting up a new licensing procedure for doctors while retaining the process of requiring hospitals to secure certificates of need from the state when purchasing such equipment.

Tonight, three members of the conference committee informally agreed that the Senate version would prevail, setting up a new licensing procedure for both doctors and hospital. Under that procedure, health providers could lose their licenses to use sophisticated equipment if regulators discover through periodic audits that it is being overused.

In other legislative action today, the House Judiciary Committee voted 12 to 6 to approve a measure that would allow an injured person to recover damages from another person or institution even if the victim contributed to his injuries. The proposal is being fought by county governments around the state, which argue that it would increase their vulnerability to large personal injury claims.

Owens' committee also killed Senate legislation that would have expanded Maryland's shield law protecting reporters from subpoenas for unpublished news.