Fresh allegations of bullying have emerged in the case of a 12-year-old schoolgirl who drowned in a Lancashire river, a tragedy that has raised concerns about the treatment of refugees in British society.

Shukri Abdi, who arrived in the UK as a Somali refugee last year, died in what her family claims were mysterious circumstances in the River Irwell in Bury last month.

Since then claims have surfaced that she was repeatedly bullied with no apparent action taken by her school, prompting campaigners to claim that Muslim girls are frequently not given the care they need.

Shukri’s family has now said that the alleged targeting of the refugee became so bad at one point that a teacher decided to remove her from school in a desperate attempt to protect her. Saynab Hareed, Shukri’s aunt, said the incident occurred earlier this year and proved the school had been acutely aware of the bullying. “She was getting bullied so badly that on one occasion one of the teachers took Shukri from school to her own house because the teacher was worried for her safety,” said Hareed.

Greater Manchester Police say they are still investigating the death and have interviewed four children who were with Shukri when she died. But they say they have uncovered no evidence bullying played a part in what they have called a “tragic incident”.

The family, however, complain it is being left in the dark and has lost faith in the force. “At first the case was closed within three days and without, we felt, a proper investigation taking place. Only after the protests did they decide to look into more details,” said Hareed.

The case has already prompted a series of demonstrations around the country, acting as a lightning rod for refugee groups who believe they have less of a stake in British society. Rakhia Ismail, the mayor of Islington, north London, said the case had raised concerns once again that ethnic groups are treated differently.

“Politicians are interested in our vote, but they do not care for the Somali community. Speaking as a mother, a Muslim and a Somali, we need to get justice for this child,” said Ismail, the UK’s first Somali-born female mayor.

Caraweelo Ali, 19, a student who was among hundreds who took part in a protest for Shukri in London last week, said: “Her death and the events surrounding it show that a black Muslim girl doesn’t matter. It has made us all question how refugees are treated in the UK.”

Meanwhile, scrutiny continues over the events that led to Shukri’s drowning. The police explanation is that they have not uncovered any suspicious circumstances and that Shukri went into deep water and got into difficulty. However, the family argues that the police have not shared any details of the interviews with the four youngsters who were with Shukri at the scene of the death on 27 June.

“We have no idea who they are, anything. They’re keeping it completely private. We just want to know how did it happen?” added Hareed.

The family also has no idea what Shukri was doing between leaving school at 3:30pm until around 11pm when police received the call that she was in the river.

Hareed said Shukri had never mentioned a desire to swim, had no towel and was wearing a hijab when she went swimming.

One Bury resident, speaking where Shukri is believed to have entered the water, said: “It’s a weird place to go for a swim, as you can see there’s hardly any water, just rocks and puddles. I’ve slipped there before and scratched my knee.”

Shukri’s school, Broad Oak Sports College, says it is currently reviewing its anti-bullying policy and procedures. Despite being repeatedly asked by the Observer to comment, it had not responded at the time of publication.

Shukri’s mother made a series of verbal complaints about bullying for more than a year and Hareed, despite living in London, also made a complaint herself, because the family was so upset about the situation.

A petition calling for the local Labour MP, James Frith, to demand an investigation into whether the school failed to properly address bullying has collected more than 77,500 signatures. Elsewhere a crowdfunding effort to support Shukri’s family has reached its £10,000 target after more than 580 people donated.