Tunisia has extended for three months a nationwide state of emergency first imposed in November, the presidency said in a statement on Tuesday.
The state of emergency was imposed after a suicide attack, claimed by Islamic State, killed 12 presidential guards in November.
Earlier in the day, Tunisia reopened border crossings with Libya, almost two weeks after clashes that erupted in the town of Ben Guerdane.
The crossing points of Ras Jedir and Wazen-Dhehibe will open initially from 7 pm (1800 GMT) to 7 am (0600 GMT), the Interior Ministry said in a statement.
The curfew hours in Ben Guerdane, near the border with Libya, were also reduced and are now from 10 pm (2100 GMT) until 5 am (0400 GMT), the ministry added.
The violence in Ben Guerdane first broke out on March 7 when unidentified gunmen attempted to seize military and police facilities there, which led to clashes with security forces.
Seven civilians, 13 security personnel and 52 insurgents were killed during the clashes in Ben Guerdane that lasted for days, according to official figures.
The violence prompted Tunisian authorities to impose a night curfew and shut down the border with Libya to prevent terrorists from entering the country.
Tunisia, widely seen as the sole democratic success story of the 2010-11 Arab Spring uprisings, has experienced a series of deadly attacks during the past year.
Last month, it completed a sand barrier and trench running half the length of its border with Libya.
Libya has been in turmoil since the 2011 overthrow of dictator Moamer Gaddafi.