Axel Rudakubana, 18, pleaded guilty at the start of his trial at Liverpool Crown Court on Monday morning (Monday night AEDT)

He pleaded guilty to three counts of murder, 10 counts of attempted murder and additional charges related to possessing the poison ricin and for having an al-Qaida manual.

A judge said Rudakubana would face life imprisonment when sentenced on Thursday.

Defence lawyer Stanley Reiz said he would present information to the judge about Rudakubana’s mental health that may be relevant to his sentence.

Rudakubana had refused to speak in court and once again refused to identify himself at the start of the proceedings.

Prosecutors haven’t said what they believe led to the rampage.

In the rioting that followed, violent groups made up mostly of men who were mobilised by far-right activists on social media attacked mosques and hotels housing migrants, tossed beer bottles, rocks and other weapons at police, and set fire to cars as they clashed with officers in dozens of cities.

More than 1200 people were arrested for the disorder and hundreds have been jailed for up to nine years in prison.

Rudakubana, who was born in Wales to Rwandan immigrants, pleaded guilty to murder in the deaths of Alice da Silva Aguiar, nine, Elsie Dot Stancombe, seven, and Bebe King, six.

Eight other girls, ranging in age from seven to 13, were wounded, along with instructor Leanne Lucas and Jonathan Hayes, who worked in a business next door and intervened. Fifteen other girls, as young as five, were at the class but uninjured.

Several months after his arrest on the day of the killings, Rudakubana was charged with additional counts for production of a biological toxin, ricin and possession of information likely to be useful to a person committing or preparing to commit an act of terrorism for having the manual in a document on his computer.

Police have said the stabbings haven’t been classified as acts of terrorism because the motive isn’t yet known.