Saeed Youssef says the 720 he sentenced included 'demons disguised in the cloak of Islam' who followed Jewish scripture

The judge who sentenced to death more than 720 alleged rioters on a single day in Egypt in April has justified his decision on the grounds that some of the accused were "demons" adherent to Jewish scripture.

In May judge Saeed Youssef sentenced 37 men to death for the murder of a policeman – and then in a separate trial gave preliminary death sentences to 683 others.

Youssef said the first 37 were "demons who came out of the depths of hell disguised in the cloak of Islam, who aimed to seize the reins of power in Egypt, loot its wealth and enslave its people".

According to several local newspapers, Youssef then described the men as "enemies of the nation" who used mosques to promote "the commandments of their holy book, the Talmud".

There are thought to be fewer than 200 practising Jews in Egypt. In addition, all the defendants had been accused of support for the Muslim Brotherhood, a group associated with anti-semitism – although many say they had nothing to do with the brotherhood or the murder.

The case was completed in just two court sessions that lasted less than an hour in total. The United Nations said they "cannot possibly have met even the most basic requirements for a fair trial".

But in his statement, Youssef said he was satisfied that there was enough evidence to incriminate the accused, whom he also convicted of burning several cars. He then condemned the defendants' lawyers for chanting criticism at him towards the end of the brief proceedings.

A spokesman for the defence team said he was disappointed in the judge's statement, which he said did not properly explain the verdict. "He hasn't added anything new," said lawyer Ahmed Shabeeb. "He just told the story all over again and only devoted about seven or eight pages out of 120 to the reasoning for the verdict."

Additional reporting by Manu Abdo