Tristram Hunt has used the ongoing row over standards at the Al-Madinah Muslim free school to launch his first major attack against Michael Gove, with a letter saying a "dangerous ideological experiment has been allowed to run completely out of control".
Despite a weekend interview in which he said Labour would support Gove's free school programme, Hunt sought to pin some of the blame for the failures of the Al-Madinah school onto the education secretary.
The school is taking legal advice after it reached a deadline set by the Department for Education for it to scrap a rule forcing all female teachers to wear the hijab and demonstrate that it has met safety requirements for children.
"I am extremely concerned that this situation could be indicative of a systemic complacency on standards," Hunt wrote to Gove this morning.
The shadow education secretary used the institution to raise concerns about the broader free school programme, in a series of questions which casts light on Labour's qualified support for the programme and highlights the areas in which it will distance itself from the government.
Hunt raised concerns over current arrangements for spotting underperformance and demanded a full disclosure of free school applications and financial arrangements.
"Given that prior to the opening of Al-Madinah free school you received a number of warnings from Ofsted regarding potential issues with the welfare, health and safety of pupils, what steps were taken to ensure that these warnings were heeded and that all issues were resolved before the school opened?" he asked.
On the issue of female teachers having to wear the hijab, Hunt asked if Gove believes there are enough regulations to prevent discriminatory practices in the recruitment of staff to free schools.
There are also reports that female students are being forced to sit at the back of the class during lessons.
"Are you satisfied that the treatment of women and girls is consistent with equality regulations?" Hunt wrote.
Secular groups have also raised concerns about attitudes to evolution and religious issues in the school's curriculum.
A prospectus highlighted by the British Humanist Association said: "If and when teachers are required by the curriculum to convey teachings that are totally against Islam (Darwinism, for example), the director of Islamic Studies will brief the relevant teachers and advise accordingly."
The school is also understood to have failed to secure Criminal Record Bureau checks on its teachers.
"In this school, as well as others across the country, your policy is being exposed as a dangerous ideological experiment which has been allowed to run completely out of control." Hunt wrote to Gove.
A letter from schools minister John Nash to the school gave it until today to satisfy a series of demands or face sanctions, including a possible loss of funding.
The school, which only opened last year, does not appear to have done so and it revealed last night that it was seeking legal advice over its treatment.
In a statement on its website, it said: "At this point, the school is struggling to see how we are being treated comparably with other schools.
"Consequently, while we intend to co-operate with the Department for Education, we have also sought the advice of the school's solicitors."
The school said it had been just an hour's notice that Nash's letter was to be published.
"To say that it came as a bolt out of the blue was an understatement," it said.
A Department of Education spokesperson said: "We've received a response from the Trust and any decisions will take into account all the available evidence."