The explosive issue of bank interest rates on credit is expected to attract attention at the Maryland General Assembly sessions in Annapolis this week.

A House Economic Matters subcommittee last week approved legislation that would allow banks to boost the interest rate on the first $500 of an unpaid credit card balance to 21 percent annually from 18 percent. At the same time, the proposal would ban banks from charging annual fees for use of the cards, the subject of a legal dispute. f

Currently, Maryland laws permits interest charges of up to 18 percent a year on the first $700 of unpaid credit card charges as well as 12 percent on the balance over that amount. Banks in the state won a legal exemption from usury ceilings in January court decision, but non-bank cards still are subject to the interest rate laws, a factor that prevents banks from charging higher rates because of competition.

Del. Steven Sklar (D-Baltimore) said the interest rate increase is a "bonanza for banks" at a time when they should get a "rap on the knuckles" for trying to impose annual membership fees after the legislature approved higher interest rate ceilings a year ago.

Other members of the House expressed opposition to the interest rate increase, and Committee Chairman Frederick Rummage said he would urge rejection. The Senate already has passed a bill that would ban annual membership fees and there was some speculation that the Economic Matters Committee will simply delete the interest rate section and pass a ban on annual fees. This week's business-related committee hearings in the Maryland Gerneral Assembly. The Virginia General Assembly regular session has adjourned and a special session is scheduled later.: MARYLAND SENATE

Tuesday: Judicial Proceedings Committee hearings on bills regarding corporations and associations, 10 a.m., Room 300 James Office Bldg.

Wednesday: Budget and Taxation Committee holds hearings on bills pertaining to collective bargaining, labor relations and disputes and income tax, 3:30 p.m., Room 100, James Senate Office Bldg.

Economic Affairs Committee considers various unemployment insurance bills, 10 a.m., Room 200, James Senate Office Bldg.

Judicial Proceedings Committee holds hearings on bills relating to condominiums and cooperative housing and home owners' associations 9:15 a.m., Room 300, James Office Bldg.

Thursday: Budget and Taxation Committee considers property tax legislation, 10 a.m., Room 100, James Senate Office Bldg.

Economic Affairs Committee holds hearings on bills relating to credit regulations and workmen's compensation, 10 a.m., Room 200, James Office Bldg.

Finance Committee considers legislation on energy conservation in buildings, 10 a.m., Presidential Wing, James Office Bldg.

Friday: Budget and Taxation Committee hearings on sales, property and income tax legislation, 10 a.m., Room 100, James Senate Office Bldg. Maryland House

Monday: Appropriations Committee holds hearings on Maryland Environmental Service Industrial Development Revenue Bonds, 2 p.m., Room 130, Lowe Office Bldg.

Constitutional and Administrative Law Committee considers bills on discrimination in insurance and housing, 2 p.m., Room hearings on municipal corporation legislation, 1 p.m., Room 140, Lowe Office Bldg.

Tuesday: Constitutional and Administrative Law Committee hearings on municipal corporation legislation, 1 p.m., Room 149, Lowe Office Bldg.

Economic Matters Committee considers legislation on industrial and home financing, retail credit accounts and industrial and commercial redevelopment, 1 p.m., Room 150, Lowe Office Bldg.

Wednesday: Economic Matters Committee takes up various insurance related legislation, 1 p.m., Room 150, Lowe Office Bldg.

Ways and Means Committee holds hearings on bills pertaining to truck fines, transportation funds, tax on gasohol and motor vehicle fuel tax, 1:30 p.m., Room 110, Lowe Office Bldg.

Thursday: Ways and Means Committee considers various property tax and tax credit legislation, 1:30 p.m., Room 110, Lowe Office Bldg.