The central zocalo saw some of the worst unrest last November as militarised state police (PFP) and paramilitaries tried to crush the opposition to state governor Ulises Ruiz.
NN journalist Nancy Davies, who has covered the unrest since its beginning, said: "How that confrontation will play out I have no idea."
Every year the zocalo in Oaxaca city has annually held Mayday protests, but the NN report stated it was uncertain whether this march would been taken as a direct confrontation of the governor.
On 26 April over 2000 government workers, in opposition to the new social security law, barged past police lines at the zocalo, although police numbers and equipment (arms and riot gear) were somewhat less than if an APPO protest was expected.
For more on these latest reports see here.
Teachers Union Section 22, with APPO Support, Prepares for its Annual Strike
Zócalo Taken by Protesters for the First Time in Six Months as Government Workers Enter the Scene Over New Social Security Law