Mexico's education secretary says the government will undertake a revision of the evaluation exam given to all teachers, which has been a focal point of protests.

Aurelio Nuno said Wednesday that officials together with the national teachers' union will make changes that better recognize the country's regional differences.

Mexico approved sweeping educational reforms in 2013, but the evaluation has been criticized by thousands of teachers who say it infringes on their labor rights. Those who do not take the exam lose their jobs.

The most radical element of the teachers' union has been behind more than a month of highway blockades and other demonstrations especially in several southern states.

Nuno emphasized that the move was not a concession to some teachers' demands that the constitutional reforms be scrapped.