Leningrad police arrested Yulia Vozneseskaya Thursday night for illegally returning to the city from Vorkuta, in the far north, where she was serving a term of exile, friends said yesterday.

At the same time police detained overnight two other Leningad dissenters, Vladimir Borisov and Natalya Kazarinova, but they were released yesterday after being fined on charges of resisting the authorities.

Voznesenskaya, 38, a poet, was sentenced in December on charges of spreading anti-Soviet slander. She was said to have returned to Leningrad to see her two children.

News of her arrest came as Pravda contended that human rights are guaranteed more effectively in the Soviet Union than in the capitalist world.

In an article vaunting the "strength and advantages of socialist democracy," the Communist Party paper continued the human right debate with the West, saying:

"The political rights and freedoms enjoyed by the individual in our country are practically unlimited by anything except one demand, namely that enjoyment of these rights by an individual should not be to the detriment of other people and society at large."

In Prague, meanwhile, a prominent Czechoslovak human rights activist was reported released from custody, but another was reported threatened with prison if he refused to leave the country.

The Austrian Socialist party newspaper Arbeiter Zeitung said writer-director Franktisek Pavlicke, a signer of the Charter 77 human rights manifesto, was released a few days ago. Pavlicek was arrested in January along with three other signers.

THe paper said that Jiri Lederer, a journalist also arrested in January, had been given the choice of emigrating or spending six years in jail.