The military government in Mali has adopted a new constitution that enhances the powers of the president and the armed forces.
It also creates a senate and demotes French from an official to a working language.
Mali has been ruled by a junta since 2020.
The opposition movement has denounced the reforms, which the electoral commission says were backed by 97% of votes cast in last month's referendum.
The official body said turnout was 38%.
Critics fear these changes make it easier for generals to break their promise of handing power back to civilian leaders after a presidential election in February 2024.
The new constitution means Interim President Col Assimi Goïta can now dictate government policy and has the power to dissolve parliament.
A legal case to have the referendum results annulled, because the vote was not held in all parts of Mali, was rejected by the constitutional court.
"Numerous irregularities" and "violations of the law" also meant the referendum result should be thrown out, according to Mali's opposition movement - made up of political parties and civil society organisations.
It has been labelled "a plot on democracy" by Ismaël Sacko - the leader of the Social Democratic Party which was last month dissolved by the junta. He told Mali's judiciary "to get its act together", AFP reports.
There was huge popular support for the military junta when it seized power after mass protests against then-President Ibrahim Boubacar Keïta three years ago. People were fed up with economic uncertainty, a disputed election and chronic insecurity.
Since then, data suggests Mali's military government has made little progress in its fightback against Islamists who control parts of the country.
But the government says the new constitution will stop the spread of the 11-year jihadist insurgency.
Mali recently decided to kick out all 12,000 UN peacekeepers in the country and is thought to employ 1,000 Russian mercenaries from the Wagner group for security back-up.
France's soldiers were ordered to leave last year and there has been rising resentment of the former colonial power and its present-day relationship with Mali, and West Africa more broadly.