Tunisian Prime minister Youssef Chahed has brought in the new measure ‘for security reasons’, his office said.
Chahed signed a circular on Friday ‘banning access to public administrations and institutions to anyone with their face covered’, a spokesman said.
The ‘security reasons’ were not explained, but Tunisia has been rocked by a series of explosions in recent days.
On Tuesday a wanted militant blew himself up in the capital Tunis after being surrounded by police.
Aymen Smiri was the suspected mastermind behind two bombings in the city on June 27, which killed a police officer and injured eight people.
The attacks prompted Britain to update its travel advice for tourists and warn of a ‘higher risk’ of attacks in Tunisia.
Tunisia’s interior minister instructed police in February 2014 to step up supervision of the wearing of the niqab as part of anti-terrorism measures, to prevent its use as disguise or to escape justice.