Elizabeth Maginnis, the local authorities' spokeswoman, said:
"Councils will resent very strongly losing the right to fire those they hire. But we are looking to make it easier to dismiss teachers who are not up to the mark."
If staff development and retraining did not work, authorities needed further powers. But staff would have to have guarantees about their rights.
Mrs Maginnis described this week's revelations as "worrying". One in five primary heads not up to it was one in five too many, she said. Heads made the most significant difference in schools.
However, she placed the blame on the former Government. "They are the hangover from 20 years of lack of investment and ideological struggle rather than a concentration on raising standards."