BUENOS AIRES (Reuters) - Argentina's government, unions and industry leaders agreed on Tuesday to raise the minimum wage by 25 percent as inflation shows few signs of cooling despite a slowdown in Latin America's No. 3 economy.

The minimum salary will rise in two stages to 2,875 pesos a month (US$621) from the current 2,300 pesos a month, although the full increase will not take effect until February.

It is the ninth straight year the government has raised the minimum wage. Salary increases are closely watched as an indication of real inflation in Argentina, where official consumer price data is widely discredited.

"I'm very pleased to be part of this agreement between workers and bosses," President Cristina Fernandez told union leaders and business leaders gathered at the Labor Ministry.

Minimum wages will rise to 2,670 pesos from September 1 and to 2,875 pesos from February 1.

Private economists put inflation at more than 20 percent in Argentina, one of the region's highest rates and about twice the rate reported by the official INDEC statistics agency.

(Reporting by Helen Popper)