A school placed in special measures has been told it risks losing its funding if urgent improvements are not made.
An Ofsted report in February rated Felixstowe Academy, Suffolk, as "inadequate" and raised concerns about the quality of teaching and leadership.
The Department for Education said it needed to be "satisfied" the school could improve for funding to continue.
Academies Enterprise Trust (AET), which runs the school, said it had a "clear plan of action to improve".
The most recent Ofsted report found a culture of bullying that was "brushed under the carpet" and pointed to poor GCSE results in which less than half of Year 11 pupils passed maths and English in 2017.
A letter from the Department for Education to AET, dated 7 March, highlighted a section of the Academies Act 2010 stating any funding agreement "may be terminated" if a school is placed in special measures.
In the "pre-termination warning notice", the national schools commissioner Sir David Carter asked to see a detailed improvement plan and monthly updates from AET regarding the school's progress.
A spokesman for AET said: "We have every confidence that the pre-warning notice will be lifted - we have recently had two other pre-warning notices and a warning notice lifted at other academies.
"We are absolutely committed to seeing similar improvements at Felixstowe Academy and are providing the appropriate support to secure that."