Workers at government-run Brazilian airports went on an indefinite strike Wednesday to press demands for higher pay and better work benefits.
The strike was called by the National Union of Airport employees (SINA).
The National Confederation of Transport Workers, of which SINA is a member, said that the stoppage affected 80 percent of the 63 airports run by the federal agency Infraero.
But Infraero said only six airports were affected: Sao Paulo's Congonhas, Rio's Galeao and those in the cities of Vitoria, Recife, Fortaleza and Salvador.
Privately-run airports such as Sao Paulo's Guarulhos, the country's busiest, and Viracopos as well as in Brasilia were operating normally.
A union spokesman said Infraero was offering only a 6.49 percent pay hike while ground staff are seeking a 16 percent increase as well and better work benefits.
The union also opposes the government's privatization program as part of efforts to upgrade the country's congested and aging airports ahead of next year's World Cup and the 2016 Rio summer Olympics.
An Infraero spokeswoman said talks with SINA were ongoing and the company was awaiting counter-proposals from the union, which scheduled general assemblies at all 63 airports for later Wednesday.
The company said contingency measures were in place to ensure essential services.
Television pictures show workers staging protest rallies at various airports, including Congonhas.
Infraero said its 63 airports handled 10.6 million passengers in June.
In December, Brazilian President Dilma Rousseff announced that Rio's Galeao airport and Belo Horizonte's Confins would be privatized during a September 2013 auction.