A school which shut after asbestos was found and a removal worker later died, will close permanently.
A council-commissioned report in 2012 found the asbestos posed a potential health risk at Cwmcarn High School.
Its 900 pupils were taught 12 miles (19km) away at Coleg Gwent’s Ebbw Vale campus, prompting parents’ protests.
It re-opened in 2014 but its numbers have halved and governors said circumstances the school has been “unprecedented”.
In a letter to parents, governors said the school would close in two years.
Gary Thomas, chairman of the governors, said:
“Faced with the halving of the school roll in the last five years, which continues to fall, combined with the number of learners in the South Islwyn region also falling and set to fall further, this makes the school unsustainable.”
Closure plans will begin in September.