Up to 5000 schools in London were closed yesterday after members of two teaching unions went on strike over their demands for an increase in the capital's cost of living allowance.

The unions' leaders are demanding teachers' London weighting is increased to match police officers who receive £6000 in central London.

The London schools minister, Stephen Twigg, said: "It's regrettable that the NUT and the NASUWT have decided to take strike action at this time. We are taking the issue of retention very seriously and recognise that there is a particular issue about teachers in their third or fourth year and why they are deciding to leave. But a stoppage is not the answer."