Rights groups including Amnesty International on Wednesday criticized a draft security law proposed by the Tunisian government to confront jihadists, saying it was "incompatible with international standards".
The bill, which is to be debated in parliament at an unspecified date, lays down stiff jail sentences for divulging state secrets or "denigrating" the army or police force.
Its wording is too vague and grants the authorities "wide discretion to make arrests for unjustified grounds" and could allow them "to charge those who expose government wrongdoing", 13 groups said in a statement.
The groups, also including New York-based Human Rights Watch (HRW), said the terms of reference were "inconsistent with international human rights standards" and with Tunisia's new constitution, drawn up since its 2011 revolution.
The unions of Tunisia's security forces, which have lost more than 70 members in clashes with jihadist militants, have been lobbying for a new security law.
"The Tunisian parliament needs to ensure not only that Tunisian security forces are able to protect people from attacks, but without trampling rights in the process," said Eric Goldstein of HRW.
Civil society groups in Tunisia have also voiced alarm at the bill, drawn up shortly after jihadists in March attacked the Bardo museum in the capital killing 21 foreign tourists and a policeman.
"The text not only protects security personnel from the terrorists but it also protects them against citizens, something very serious," said Ridha Sfar, a former minister in charge of national security.
Even some advocates of the bill are cautioning that it goes too far.
"The principle of this law is to protect us... but now we have a bill that is causing controversy," Chokri Hammada, a spokesman for the internal security forces' union, told AFP.
"We want a new version guaranteeing the security of law and order personnel without it being a tool to harm freedoms. We need... moral support and not tension with the people," he said.
Tunisia has won international praise for its post-revolution elections held in 2014.
But civil society groups fear a return to the authoritarian ways of the ousted regime of Zine El Abidine Ben Ali with the return to public life of figures close to the longtime autocratic ruler.