Catholic teachers to strike in NSW

Teachers from 200 Catholic schools across NSW will strike over concerns that class sizes could increase while resources are lost under a new employment agreement.

Higher duty allowances would be stripped, class size restrictions scrapped, sick leave reduced and meal breaks taken away under a new employment proposition from Catholic employers, the NSW Independent Education Union (IEU) says.

"Our members have overwhelming endorsed stop-work action ... it's probably 1.5 per cent who voted against it," NSW IEU general secretary John Quessy told AAP on Monday.

Teachers are already stretched, said Mr Quessy, and taking away resources, such as teachers' assistants, while increasing class sizes would "remove the safety net".

On Tuesday Catholic school teachers and IEU members from Sydney and the Central Coast will stop work for three hours from the start of the school day.

Their colleagues in Parramatta, Penrith, the Blue Mountains and the Hills district will take the same action on Wednesday.

But Mr Quessy said schools would still be staffed.

"Schools will not physically close. There will be some level of supervision because principals certainly will be there," he said.

"Parents should check with the school. But it will be business as usual from about midday."