The latest exclusion figures for schools in Wakefield have been branded "worrying" by one former head teacher.
A total of 11 children were expelled across the district in September, while 510 temporary exclusions were handed out by school leaders in the same month.
A "similar" number of pupils were told to leave school in July, just before schools' summer break, Wakefield's children and young people scrutiny committee were told on Wednesday.
Education professionals have greeted that news with concern, as historically more children have been excluded towards the end of term, rather than at the start.
Committee chair Councillor David Jones, a former head at a high school in Pontefract, said: "Looking at those figures for September, they’re worrying, because you wouldn’t expect to see exclusions to increase until November.
"I have to say I’m concerned about that.
"In September, you think about everyone being enthusiastic to go back to school, so I think we need to have a review into why that’s the case."
The numbers of children being off-rolled from schools are rising across the UK, with one senior council officer saying last year that some principals were "encouraging home schooling" among unruly pupils.
The practice has been linked to schools trying to improve their results in an increasingly competitive education system.
Other committee members offered views about the findings, with former councillor Monica Graham suggesting that pupils were not being "given the chance" to improve their behaviour.
Another, Councillor Celia Loughran, suggested that pupils from troubled homes may be more prone to misbehaviour in September because of "trauma" they'd experienced during their six-week break.
Council officers have promised to publish a numerical breakdown of how many children have been excluded from each local school.
Coun Maureen Tennant-King suggested that an influx of new staff at the start of term might be contributing to the issue.
She said: "They’re clamping down really early in the school year, and if you’ve had a quick turnover of staff in summer, the new staff may have seen behaviour which they see as unacceptable, and they’re taking action on it much quicker."
Local Democracy Reporting Service