VIENNA, Austria (AP) _ A leading Latvian human rights activist said Wednesday that Soviet authorities are cracking down on prominent dissidents by giving them a choice: exile or Siberia.

Janis Barkans, a member of the Helsinki '86 human rights group in the Latvian capital of Riga, said Soviet authorities stifle dissent by forcing opposition activists into exile instead of throwing them in jail.

Helsinki '86 has been monitoring Soviet compliance with human rights provisions laid down in the Helsinki Final Act.

''They think it's better for them in this situation to send us off rather than put us in prison,'' Barkans told a news conference. ''I don't agree with this. I wanted to stay in Latvia, but I was forced to leave.''

Barkans, 28, became temporary leader of Helsinki '86 when its founder, Linards Grantins, was imprisoned last spring.

Barkans, his father, and another member of Helsinki '86, Raimunds Bitenieks, arrived in Vienna on Sunday. He told reporters the KGB threatened to send him to Siberia if he did not emigrate.

Barkans said he and Bitenieks were threatened with physical injury unless they left Latvia before Nov. 18, when several thousand people demonstrated in Riga to mark Latvian independence. He said both were placed under house arrest to prevent them from taking part.

Latvia was a sovereign republic until 1940.

Barkans said he hoped to travel to Sweden next week and settle there. Bitenieks said he planned to go to West Germany.