MOSCOW (AP) _ The Soviet legislature on Tuesday approved for nationwide discussion a proposal to loosen the state's hold on property, which backers say is the centerpiece of economic reform.

Tass said the bill would give stock companies, collectives and cooperatives equal rights with the government, which owns 80 percent to 90 percent of the property in the vast country.

A blueprint for economic reform being discussed at a three-day conference of academics and managers that started Monday in Moscow says loosening controls on ownership ''is the fundamental basis for citizens' economic freedom.''

''Renovation of property relations leads to settling the key problem of socialist economy: formation of long-term interest of enterprises and their staffs in optimum proportions of consumption and accumulation,'' the report said.

A report to be adopted by the conference is expected to become the basis for a detailed effort to heal the Soviet economy, which is suffering from strikes, shortages, hoarding and a near-worthless currency.

The program is likely to be presented to the Congress of People's Deputies parliament when it reconvenes Dec. 12.

The bill, along with several options, will be published but indicated it is unlikely it will receive final legislative approval soon, Tass said. The Supreme Soviet rejected a call to bring the question up for final consideration at the Congress.

Some legislators want the question to go to a nationwide referdenum, it said.

Tass noted some legislators argued for the full legalization of private property, but Premier Nikolai I. Ryzhkov rejected that as being against the will of the people.

Sergei Alexeyev, chairman of the Supreme Soviet's Committee on Legislation, told the legislature the bill gives land and natural resources to the people of the region and limits ownership by the national government to that which is ''necessary for meeting the union and inter-republican requirements, national defense and security needs.''

That apparently represents a partial victory for reformers in the Baltic republics, who have demanded control over their own natural resources. But Tass said Baltic legislators pushed for exclusive control over all their republics' land and natural resources.