Prince George's County Executive Winfield M. Kelly Jr. yesterday threatened another series of budget cuts that would delay the opening of the Laurel Hospital, eliminate allowances for appointed commissioners and suspend special grants to county towns.

Although the cuts would lead to only $4.2 million in savings, they would directly affect thousands of county residents.

Since the first of the year Kelly has chiseled away at the budget, cutting out only the most popular programs and projects in a effort to force the General Assembly to adopt his tax proposals.

Kelly's hope is that angry citizens upset over the loss of a cherished project will badger their state representatives who will then pass into law one of Kelly's tax proposals.

Yesterday's budget cuts could have just that affect, in the opinion of Del. Ann Hull (D-Prince George's) who is speaker pro tem of the House.

Municipalities such as Hyattsville and Greenbelt pay county taxes to support the county police force and levy their own taxes to support their town police forces. For years the 28 county municipalities have depended on a special grant, called the tax differential, to help pay for police.

The delay in opening the Laurel Hospital would save the county some $3 million but would leave standing a $20 million hospital that has never been used. The hospital was scheduled to open in two months.

The elimination of an allowance for board members and commission appointees offers only $200,000 in savings. It would affect about 200 people who received patronage appointments to the Landlord-Tenant Commission, the Human Relations Commission and other boards but no salary other than these allowances.

Kelly has yet to give a precise explanation of the fiscal crisis that has led to these budget cuts. He will present his budget in detail to the county delegation the Assembly Thursday and ask for the delegation's endorsement of one of his tax programs.