A young human rights activist has been warned by the Soviet secret police that he has until Tuesday to answer their questions about jailed dissident Yuri Orlov or himself face charges that could mean seven years at hard labor and five more in Siberian exile.

The activist, Alexander Podrabinyek, 23, said he would refuse to answer any KGB police questions when he goes to Lubyanka Prison Tuesday morning for another round of interrogation. Podrabinyek is a member of the "Working Committee on the Use of Psychaitry for Political Purposes," a group of seeking to record allegations of forcible psychiatric treatment as a means of political punishment in the Soviet Union.

Orlov, a physicist, was arrested in February at the beginning of a Kremlin crackdown on the tiny but vocal dissident movement in this country. His arrest prompted expressions of concern from the White House. Orlov has since been charged with anti Soviet activity, which carries up to three years' imprisonment.

He was head of a Moscow-based citizens' group that has tried to access Soviet compliance with the human rights provisions of the Helsinki accord on European Security signed by 35 nations in 1975. A meeting to assess the performance of the signing nations is scheduled for October in Belgrade.

Podrabnyek said investigations have questioned him about his ties to Orlov during two interrogation sessions this month, each of which lasted about eight hours. He has been ordered to report to Lubyanka at 10 a.m. Tuesday. He said he was "assured" by authorities that.

"They can charge me with anti-Soviet propaganda and assured me I will be charged" if their questions are not answered. Anti-Soviet propaganda is one of the most serious code, carrying maximum penalties of seven years in a labor camp and then five years of intermal exile in a remote part of the country.

Podrabinyek said the authorities promised him that if the did cooperate, no charges would be pressed and he would be allowed to leave the Soviet Union. Emigration is a goal of many dissidents, many of whom are Jews, seeking to live in Israel. Podrabinyek said, however, that he has not applied to emigrate. "I just wish the KGB would emigrate," he told reporters.

"Other dissident sources said today that the method of handling Podrabinyek amounted to "blackmail and threats." Podrabinyek said his interrogators expressly warned him that food and medical treatment in prison is "very bad."

Earlier this week, 40 nuclear scientists from the United States, Britain, France and Italy attending a symposium on high energy particles at nearby Protvino sent a message of condolence to Orlov, who is a specialist in that branch of nuclear physics.

Podrabinyek is a medical attendant, a job described to reporters today as being similar to an ambulance attendant, but with greater responsibility. He said at a press conference at Orlov's apartment today that he knows of special KGB ambulance squads that are used to carry political prisoners to psychiatric hospitals for incarceration. These convert squards are kept separate from regular ambulance teams, he said. "They keep the real workers at arms' length," he told reporters.

The attendant said he was seized by the KGB during a search of his apartment March 10. He said the secret police found a card file in which he was keeping data on psychiatric cases and also seized a copy of a book. "The Medicine to Punish." Which he said he worte to recount examples of forced psychiatric treatment for political prisoners.

On the basis of these materials, he said, he was jailed and interrogated for 15 days in March. He was eventually released and was free until the questioning began this month. No charges have been filed against him but apparently the materials seized by the police would severe as the basis for any charges.

Podrabinyek said he has been collecting documents on psychiatric cases for several years. He added that althought police seized his own copy of his book, other copies are already circulating through "samizdat," the underground network in which works that cannot find official publication are circulated privately among some intellectuals and dissidents here and in other Soviet cities.