(CNN) -- Two teachers in Colombia have been killed in as many months, a prominent alliance of trade unions said Friday, calling on the government there to do more to bring those responsible to justice.
Dionis Alfredo Sierra Vergara and Alejandro Jose Penata Lopez were both members of the Teachers' Association of Cordoba, according to a statement from the International Trade Union Confederation, or ITUC, the world's largest federation of trade unions.
Sierra Vergara, a primary school teacher, was reportedly killed on May 15. Citing an eyewitness, the union confederation said he received a call on his cell phone. Where he went outside to answer it, Sierra Vergara was attacked and shot three times.
Penata Lopez was murdered on June 20, according to the ITUC. He disappeared after he left school. His body was found later having shown signs of torture, having reportedly been hung with barbed wire.
The men were the latest trade unionists apparently targeted in Colombia, which the ITUC calls the most dangerous country in the world for union members.
In the department of Cordoba, alone, 20 teachers have been killed since December 2008, according to the ITUC. At least six of those teachers -- including Sierra Vergara and Penata Lopez -- were reported slain this year.
"The context of almost total impunity for these murders has led to an alarming humanitarian crisis in the education sector and has put teaching and trade union actions at risk," the trade union alliance said Friday. "(It) clearly refutes the Colombian governments' statements in international forums about human rights' improvements."
According to the group's 2011 survey of 143 countries, Colombia is the deadliest country in the world for trade unionists.
Of the estimated 90 trade union members killed in 2010, 49 of them were in Colombia. Another 20 people were reported to have escaped attempted attacks that year in the South American nation.