A secret new anti-terror law being drawn up by the Saudi authorities would "strangle peaceful protest", Amnesty International has said.
The BBC has been shown a classified copy of the draft law showing a number of measures Amnesty said would severely restrict human rights.
These include lengthy detention without trial, restricted legal access and increased use of the death penalty.
But a Saudi official said it was directed at terrorists, not dissidents.
The Saudi government has so far declined to comment, but the senior official, who did not want to be named, confirmed the existence of the draft law and did not dispute the clauses contained in it.
Amnesty International's Middle East press officer James Lynch told the BBC the draft law - a copy of which was leaked to the human rights group - "seeks to entrench some of the most repressive practices that Amnesty has been documenting for years".
Among the measures proposed is a broadening of the definition of a terrorist crime to include any action deemed to be "harming the reputation of the state" or "endangering national unity".