Hardline Catholics have reportedly sent hate mail to some of the loyalist protestors involved in the six-week-old dispute outside Holy Cross primary school in north Belfast.
The printed notes, which were reportedly sent to at least seven Protestant homes, said: "Stop the protest at Holy Cross school or you will be targeted by the north Belfast Catholic Reaction Force."
The threat comes after tentative talks between Catholic parents and loyalist protestors last night failed to achieve a breakthrough.