The extension was announced Friday by Prime Minister Pōhiva Tu’i’onetoa.
This means, the nighttime curfews remain in force across Tonga until next month.
Kaniva News reports Tonga is still Covid-19 free.
The government set new rules governing public behaviour to help stop the spread of Covid-19 that came into force last week.
Under the rules, the boarder will remain closed until June 12 and there is a nighttime curfew from 8pm to 6am.
Liquor licensed nightclubs and kava clubs must close.