An Egyptian court has confirmed death sentences against the leader of the outlawed Muslim Brotherhood and at least 182 of his supporters.

The court's decision came two months after it referred the case against the Brotherhood's "general guide", Mohamed Badie, and hundreds of others to the state's highest religious authority, the grand mufti, the first step towards imposing a death sentence.

They were charged over violence that erupted in the southern Egyptian town of Minya in July, in the aftermath of the army coup that ousted then president, Mohamed Morsi, a senior Brotherhood member. One senior police officer was killed in the violence.

Lawyers say the ruling can be overturned on appeal. It was not immediately clear how many sentences had been confirmed, with the lawyers giving estimates ranging from 182 to 197. In either case, it would be largest mass death sentence to be confirmed in Egypt in recent memory.

Lawyers boycotted the opening of the trial on 25 March to protest an earlier mass death sentence by Judge Said Youssef. A month after that session, the judge sentenced 683 people to death, including Badie. Of the 683, all but 110 were tried in absentia, according to defence lawyer Khaled el-Komi.

Death sentences issued for those in absentia are automatically cancelled in Egypt if they turn themselves in or are apprehended, and a retrial is ordered.

The case springs from an attack on a police station in the town of Adwa near the southern city of Minya on 14 August in which one policeman and one civilian were killed. The attack was carried out in retaliation after police killed hundreds while dispersing a sprawling Cairo sit-in by Morsi supporters.

The death sentences sparked international condemnation and raised questions about the independence of the judiciary.

Mohammed Tosson, a representative of the defence team, said that 183 people were sentenced to death, four received life sentences and 496 were acquitted. Those sentenced to death include a Coptic Christian and a blind man, said another lawyer, Mohammed Abdel-Wahab.

The charges ranged from sabotage and terrorising civilians to murder.