No more English language medium schools should open in Cardiff, a former leader of the city's council will suggest.
Phil Bale, leader from 2014 to 2017, will suggest all new schools in the city should be Welsh language or bilingual schools.
In a speech at the Tafwyl festival, Mr Bale will say this is because pupils leave English medium schools with "little or no skills in Welsh".
Cardiff council has been asked to comment.
- Education key to addressing Cardiff inequalities
- Disney cartoon, sword and chips in Welsh councillors' gift list
Mr Bale is expected to say in his speech, seen by the BBC, that the city "needs to be bold in decisions on whether new build schools in Cardiff should be English or Welsh Medium in the future".
"If Cardiff is serious about reducing the significant number of pupils leaving Cardiff's English medium schools with little or no skills in Welsh, then reverting to a policy of only opening either bilingual or Welsh medium schools also now needs serious consideration," Mr Bale, who was replaced by Huw Thomas in 2017, is due to say.
Welsh language campaign group Cymdeithas yr Iaith Gymraeg has called for more Welsh-medium schools to be built in the city.
Last year the group held a rally in the capital, saying the council needed to open another 10 schools in the next five years to help meet a Welsh Government target of one million Welsh speakers by 2050.
But at the time Cardiff Council said it was meeting current demand and was committed to ensuring future provision for Welsh speakers.