The education ministry announced the move in a statement on Wednesday.
"The ongoing holiday for educational institutions has been extended to Aug 31. All kinds of educational institutions across the country will remain closed until then."
The government announced the closure of all schools and educational institutions in the country on Mar 17 following the outbreak of the novel coronavirus. It later ordered the shutdown of offices, workplaces and public transport services under a nationwide lockdown which came into effect on Mar 26.
Offices and public transport services later reopened on a limited scale at the end of the 66-day lockdown on May 31.
The rampant epidemic has also resulted in the postponement of the HSC and equivalent examinations originally slated for Apr 1.