Ali Louati, Associated Press
Tunisian's president Beji Caid Essebsi, left, lays a wreath in memory of the victims of the terrorist attack at the Bardo Museum in Tunis, Sunday March 22, 2015. The two extremist gunmen who killed 21 people at a museum in Tunis trained in neighboring Libya before caring out the deadly attack, a top Tunisian security official said.

TUNIS, Tunisia — The curator of the Tunisian museum targeted by a terrorist attack announced Tuesday that the reopening has been postponed, for logistical and security reasons.

The government meanwhile has announced new measures to close mosques not regulated by the government and to boost security around tourist sites and at the borders.

The National Bardo Museum in Tunis was scheduled to reopen Tuesday for the first time since gunmen opened fire on tourists March 18, killing 21 people.

Curator Moncef Ben Moussa told The Associated Press that there would be a "symbolic" ceremony Tuesday for select guests, but the museum will not open to the public until Sunday. He blamed the delay on organizational problems.

Museum spokeswoman Hanane Srarfi said the problems were primarily logistical, but added: "There is obviously also the security aspect being taken into account."

Officials have said none of the museum's major archaeological treasures suffered damage.

Tuesday's ceremony will include a tribute to the victims of the attack and a concert by the Tunis symphony orchestra. Activists also plan a "march against terrorism" to the museum.

Authorities have arrested several people in the attack, the worst in Tunisia in 13 years, and are still hunting for the suspected mastermind. Five leading security officials were fired after the attack, and a police officer charged with surveillance of the museum was jailed.

After a meeting of top security officials late Monday, the government announced that unregistered mosques — believed to number 187 — would be shuttered, along with those preaching extremist doctrines.

Many of the estimated 3,000 Tunisians that have gone to fight with extremist groups were believed to have been radicalized at certain mosques.

The government also said electronic surveillance systems would be installed in public spaces and checkpoints at the entrance to cities would be toughened.