A teachers' strike for higher pay in Argentina forced the suspension of classes Monday at the start of the new school term, in a challenge to President Mauricio Macri.
Thousands of teachers dressed in white marched in the capital Buenos Aires to mark the start of the two-day stoppage.
They are demanding a hike in wages greater than the 17 percent estimated inflation rate this year in recession-hit Argentina.
In Buenos Aires province, the government has rejected a demand for a 35-percent raise in teachers' pay.
Nationally, the government is refusing to open wage negotiations with teachers.
It wants to limit pay raises to the same level as inflation for all professions.
Macri dismissed the strike as "opportunism," as he spoke at an event to mark the start of the school term.
Argentina's economy shrank by 2.3 percent last year. On Monday, ratings agency Moody's lowered the country's outlook from "positive" to "stable."
Mid-term legislative elections in October pose a key test for Macri and his economic reforms.
Three major labor unions have called for demonstrations on Tuesday.