The KNU signed a ceasefire with the Karen State government and another with the national government's peace committee, headed by Railways Minister Aung Min.
"The ceasefire is effective immediately," Aung Min said.
The KNU side said the agreements were a good first step.
"We want to see the peace process go forward," said KNU Secretary David Taw.
The KNU, which has been fighting Myanmar central governments since January 1949, is one of a dozen insurgencies that have struggling for the autonomy of their traditional territories for decades. //DPA