The authorities in Egypt have continued their crackdown on the Muslim Brotherhood, detaining another 38 people on Thursday after the latest bomb blast.

Five people were injured, one seriously, after an explosion in the morning smashed the windows of a bus in Cairo.

The attack happened the day after the government branded the Muslim Brotherhood a terrorist organisation, blaming it for an earlier suicide bombing on a police headquarters in the northern city of Mansoura.

“They did this to stop us from voting in (next month’s) referendum. We won’t be frightened. We will definitely take part. We will also take to the streets and ride buses. They can’t intimidate us like this,” said Cairo resident Nadia Mohamed.

The authorities said other devices were found near the site of the Cairo bus blast and defused.

Almost half of Thursday’s arrests took place in the Nile Delta, the region where Tuesday’s suicide bombing took place.

The further crackdown comes even though the Brotherhood condemned the attack and denied carrying it out.

“The accusation that the Muslim Brotherhood are terrorists has not been confirmed. This decision was taken in a hurry and the prosecution has not ruled on it. Meanwhile, the explosions that the government accused the Muslim Brotherhood of causing were perpetrated by other groups,” said Aya Alaa from the activist group “Women against the Coup”, speaking at a briefing given by the Brotherhood’s supporters and allies.

From now on, anyone taking part in Brotherhood protests will be jailed for five years, interior ministry spokesman Hany Abdel Latif told state TV. Jail terms for those accused under the terror law stretch up to life imprisonment. “The sentence could be death for those who lead this organisation,” he said.