Soviet officials have told the United States that Moscow intends to revise laws used for decades to crush political dissent and religious observance, a senior State Department official says.

Assistant Secretary of State Richard Schifter said in an interview last week that the Kremlin plans later this year to introduce measures that would repeal a law making it a crime to "defame" the Soviet state and ease a statute banning the teaching of religion outside the family.The State Department says thousands of Soviet dissidents and religious observers have been convicted and imprisoned under those broad statutes in recent decades.

Soviet experts have said the changes, if approved and enforced, could prove to be of "historic" importance.

"In the Soviet Union, there's a yearning to be free," said Schifter, the Assistant Secretary of State for Human Rights and Humanitarian Affairs.

"The Soviet leadership has an increasing awareness of how they look in the world as a result of their failure in human rights. The fact that this administration has made (Soviet human rights) an issue has speeded up the process," he said.

Schifter said Soviet officials described the plans to him during U.S.-Soviet human rights meetings in Washington Sept. 22 and 23. These working groups convened while Soviet Foreign Minister Eduard Shevardnadze met with Secretary of State George Shultz.

Schifter said the Soviets discussed Soviet leader Mikhail Gorbachev's plans to propose new laws for public discussion by the end of the year and submit them to the legislative Supreme Soviet soon afterward.

Among the changes detailed by the Soviets, Schifter said, were plans to lengthen judges' terms to make the judiciary more independent of government influence and to allow religious groups to perform charitable work.

The Soviets also described new regulations they had drafted to lower barriers to emigration by Soviet citizens, the State Department has previously said.

In trying to ease restrictions on political dissent, the Soviets are said to be changing two articles in their criminal code.

The law to be repealed, Article 190-1, bans "circulation in any oral form of fabrications . . . which defame the Soviet state and social system." A department official said the Soviets also intend to tighten the notorious Article 70 that bans "anti-Soviet agitation and propaganda."

The State Department says the Soviet Union used these laws to prosecute many of the 750 political prisoners who in early 1987 were held in prisons, labor camps and mental institutions.

A department official estimated that under the anti-religion statute, between 40 and 50 Soviet citizens have been imprisoned for religious activities.