The Cabinet committee drafting an urban policy statement, for President Carter has concluded that the federal government itself may be a main cause of the cities' present practions.

While recommending a vareity of new programs that could, if approved, add several billion dollars to Carter's next budget, the Urban and Regional Policy task force says Washington could help a great deal by halting or changing some of the things it does that inadvertently hurt cities.

A draft of the report being readied for the White House criticizes tax law, purchasing policies, the sitting of federal facilities, the construction of highways and the distribution of housing subsidies as contributing to the plight of many older cities and their inhabitants.

It presents a variety of proposals for helping those cities, centering on job-creation programs but ranging into the areas of education, health and social services.

The report urges greater reliance on state governments to close the imbalance between center cities and suburbns, in its latest version, suggests the possibility that cities might buy and operate factories that private industry decides to close.

No total price tag has yet been placed on the proposals, which will go to the White House next month as the basis for presidential decisions on urban programs in the budget Carter will send Congress in January.

However, officials said that Carter had not told this task force - as he originally told those drafting his welfare revision program - to avoid any proposals entailing extra costs. The President eventually relented on the no-extra-cost stipulation on welfare revision.

The lead role in drafting the proposals was given by Carter to Patricia Roberts Harris, secretary of Housing and Urban Development. Assistant HUD Secretary RObert C. Embry has been chairing the interdepartmental task force, which also includes members of the White House domestic policy staff.

While officials said many decisions remain to be made at the White House, the major thrust of the committee recommendations is the provisions of more jobs for the hard-core unemployed of the center cities.

The cost of this proposal is suggested by the fact that an expansion of the Comprehensive Employment and Training Act (CETA) program from 725,000 jobs to 1.2 million, as suggested for next year, would ask for $4.7 billion in itself.

Other proposed employment programs, if approved could add several billion dollars to the budget.

Such expenditures could raise severe problems for Carter's budget-balancing strategy, but officials of the urban task forces sais its members were convinced that new jobs must be at the centerpiece of an urban strategy.

"The basic problem with the cities," said one official, "is that they don't have enough of an economic base to employ their own residents. By pursueing a policy of neutrality on the location of jobs, our government in the past has actually provided incentives for the emigration of jobs.

"Our view is that we need a conscious policy of creating jobs - targeted in the cities who need work."

It was from that the task force moted to considering what one official called "the need for new forms of ownerwhip" of in-city factories.

One official said that the proposal contemplates that if a steel firm decided to shut down a big-city plant with a low operating-profit margin, the city and the workers might buy the plant and modernize it with a federal loan in order to avoid the loss of jobs.

While the provision of jobs in the cities is the main course recommended by the study group, its draft report also suggests the federal government could do much to help the cities without spending more money.

Programs that are now diffused in their geographical impact could be concentrated on the needy residents of impoverished cities, it suggests. And other government programs that hurt the cities could be stopped or changed.

The last view is reinforced by an independent study by the Rand Corp., a private think-tank, and released today by the National League of Cities.

It concluded, in terms similar to those of the Carter task force, that-broad federal policies have had a greater, though unintended, impact on urban development than deliberate urban programs." And it said that overall, "these policies have contributed to the decline of central-city population and employment."

Examples of the sort of federal programs that have unwittingly damaged the cities by speeding the decentralization of population range from the construction of the interstate highway network to the provision of mortgage-interest deductions for home-buyers.

The interdepartmental task force recommends that the Office of Management and Budget require an "urban impact assessment" of all federal programs and says that HUD should play a much stronger role than it has as the "urban advocate" within the government, in much the same way that the Agriculture Department looks after farmers, or the Commerce Department does for industry.

"Nothing less than a comprehensive shift in the whole arsenal of federal actions affecting cities is required if city economies are to function and provide the wealth and work opportunities needed to support local institutions and people," the task force's draft report declares.

"Federal taxes must be altered to generte incentives for private investment to flow into cities. Ample credit must be available to finance these investments. Federal government purchases of goods and services must be used to provide a market for the produce of city economies. Federal facilities must lead the way back to cities for other sectors of economic activity."

The task force has tentatively recommended creation of an "Urbank" with an initial funding of $2 billion to help finance job-creating projects in the cities.

However, it takes a cautious approach to federal underwriting of city borrowing and says the issue of tax-exempt municipal bonds should be studies carefully before any change is made.

In terms of city-suburn relations, the main thrust of the draft report is that the states, rathan than Washington, D.C., are best able to cut down the disparties within metropolitan areas. It suggests, however, that there could be federal financial incentives for states that move in this direction.