Counter-terrorism legislation proposed by the French government will "normalize abusive practices," undermine personal freedoms, and may fuel prejudice against the Muslim minority, Human Rights Watch (HRW) said on Tuesday.
A bill presented last week would enshrine curbs on fundamental rights in law if approved by parliament, the rights group said.
Newly-elected President Emmanuel Macron wants the legislation to replace temporary emergency powers in place since Islamist militants attacked Paris in 2015.
"Instead of truly ending France's 19-month temporary state of emergency, the government is making some of its far-reaching powers permanent, but with little effective court oversight," HRW's Kartik Raj said.
"France needs to find a way to end its state of emergency without normalizing abusive practices."
France, home to Europe's largest Muslim minority, has grappled with a response to homegrown jihadists and foreign militants following attacks that have killed more than 230 people since early 2015.
The draft bill envisages extending police powers to stop and search people or conduct house searches. The law would also give officials more discretion in deciding when to invoke a risk of terrorism as justification for curbs on freedoms.
Mr. Macron has assured the European Court of Human Rights the legislation would respect public freedoms.
"As the text stands, it [the law] could, for instance, be used arbitrarily to prohibit any meeting at which ideas or theological concepts associated with conservative interpretations of Islam, such as Salafism, are expressed regardless of whether there is any demonstrable connection to criminal activity," HRW said.
"Poorly worded laws that are likely to lead to closing solely Muslim places of worship may also help feed anti-Muslim rhetoric and prejudice prevalent in wider society," it said.
Several mosques have been shut temporarily under the state of emergency, imposed after Islamist gunmen and suicide bombers killed 130 people in a concert hall and restaurants and bars in Paris in November 2015.