A coalition of 10 international human rights groups on Friday slammed Tunisian President Kais Saied for dealing “a deep blow to judicial independence” after he fired dozens of judges.

Saied issued a presidential decree on June 1 in which he awarded himself the power to fire judges, and then sacked 57 after accusing them of corruption and protecting “terrorists” – accusations the Tunisian Judges’ Association said were mostly politically motivated.

Critics also have said his move further cemented a power grab that began last year when he dismissed the government and disbanded an elected parliament – adding to concerns that Saied has put the only country to emerge from the 2011 Arab Spring with a sustained period of democracy back on a path towards undemocratic rule.

Saied has begun to govern by decree as he has faced strong domestic and foreign criticism that he has been vying to consolidate a one-man rule. But the president, who rejected the accusations, said he sought to save the state from collapse and reform institutions after “a decade of ruin”.

The rights groups – including Human Rights Watch, Amnesty International, and International Alert – said in a joint statement that Saied’s moves were an assault on the rule of law and he should immediately revoke the decree and reinstate the judges.

“The expansion of the president’s powers to summarily fire judges is a frontal assault on the rule of law,” the groups said.

“Saied has removed whatever autonomy the judiciary in Tunisia still was able to exercise,” said Salsabil Chellali, Tunisia director at Human Rights Watch.

Amnesty International and Lawyers Without Borders also put their names to the statement, which called for the president to revoke the decree “immediately”.

“The decree is the president’s latest move to concentrate powers in his own hands,” the statement said.

Saied’s decision drew anger from the judges, who went on a week-long strike and were heading for an extension to a second week.

Among the judges fired was Youssef Bouzaker, former head of the Supreme Judicial Council whose members Saied replaced this year.

The council had acted as the main guarantor of judicial independence since Tunisia’s 2011 revolution that introduced democracy

The president has planned to hold a referendum on July 25 – the first anniversary of his consolidation of power – on a new constitution, in advance of elections in December.

The text of that constitution has yet to be presented after a national consultation exercise that largely failed to generate participation by citizens.