An independent school educating some of Norfolk's most vulnerable children has been warned by inspectors for a second time that it must improve.

Include Schools Norfolk, which runs schools in Norwich, King's Lynn and Great Yarmouth and charges annual fees of £21,000, has been ranked by Ofsted as requiring improvement after an inspection in March.

Ofsted said an action plan put together after the school's first "requires improvement" judgement two years ago had been deemed unacceptable on three separate occasions and that leaders had more work to do "to support pupils to make the progress they should".

The school, run by charity Catch22, takes students referred by the local authority and currently has 94 boys and girls aged 14 to 16 on its roll, many of whom have been excluded from mainstream schools, special schools or pupil referral units. Almost two thirds of its students receive pupil premium funding, a government top-up to help educate disadvantaged children, while some have mental health problems or other learning difficulties.

During their visit to the school's three sites in March, the inspection team found the school's self-evaluation lacked precision and that the inaccuracy of some assessments was having a negative impact on the planning of teaching and learning.

Inspectors said attendance "remains a challenge", with a high number of pupils regularly absent, and that behaviour was too variable.

They added that exclusion rates during the autumn term had been high among the new intake of pupils as they were "testing out their boundaries with staff", but had since fallen.

More positively, the report said the school's curriculum met the needs and interests of pupils and that they were motivated and made good progress when teachers had high expectations.

Parents and carers told inspectors that their children were well looked after and well taught at the school.

Include Schools Norfolk headteacher Philip Hinchliffe said: "While Ofsted identified areas where the school is performing well such as pupil motivation and staff support, we recognise there are some areas where we need to focus greater attention.

"We are already implementing an action plan to ensure we continue to improve in these areas so we can meet the complex needs of our pupils and give them the best possible chance to move on to the next stage of their education."