Inspectors in Wales have cracked down on an evangelical Christian sect that bans computers and sex education - weeks after it was allowed to register 38 schools in England.
Estyn, the education watchdog for Wales, said the only school run by the Exclusive Brethren in the principality failed to promote respect for other cultures.
The private faith school, based in an office block in a Swansea business park, also failed to provide pupils with adequate career guidance or personal and social education. It has been given provisional registration and must address the shortcomings or could face closure.
Estyn's ruling follows Ofsted's decision to register all the Brethren's schools in England, which are run with the same hardline religious ethos, a move that has outraged secular groups. Two Brethren schools in Scotland have been provisionally registered.
Chris Brown, chief executive of Keystone Education Trust, the Swansea Brethren school, welcomed most of the Estyn report and blamed the shortcomings on being a "new and very small school".
A careers adviser would be appointed, he said, and the children already studied other faiths, including Islam.
"We want to produce well-rounded pupils. Not all of our teachers belong to our faith and pupils are free to discuss other religions," said Mr Brown.
Keystone now hopes to meet the Welsh Independent Schools Council, which offers guidance and support to potential members in the independent sector.
Plaid Cymru said it was "worrying" for any school to fall short of the registration standard. Peter Black, Liberal Democrat chairman of the National Assembly's education and lifelong learning committee, said he found it unbelievable that pupils were not taught vital computer skills and sex education.
Keystone opened in September 2003 and is affiliated to the Focus Learning Trust, which provides support to all Brethren schools, and employs 14 part-time teaching staff who are in charge of 21 pupils - 15 boys and six girls aged 11 to 17.
Pupils are forbidden to use computers and learn typing instead. They are taught Bible studies rather than RE.
Estyn found the Swansea pupils to be "well-motivated, diligent, mature, respectful and committed". But weaknesses were found in science, PE and music.