Thousands of tourists have left Tunisia since Friday's (local time) attack, which has shocked the North African country that relies heavily on tourism for jobs and foreign currency revenues.
Britain's Foreign Office warned that Islamist militants may launch further attacks in Tunisia after a gunman opened fire on the Imperial Marhaba resort in the deadliest such attack in Tunisia's modern history.
At least 15 Britons were among the dead and wounded along with German, Irish and Belgian nationals in Sousse. The health ministry says at least 40 people were wounded without giving any details of their nationalities.
"We are going to deploy 1,000 armed police to protect hotels and tourists," Tunisian Interior Minister Najem Gharsalli told reporters late on Saturday night.
Since its 2011 uprising to oust Zine El-Abidine Ben Ali, Tunisia has made a peaceful transition to democracy with a new constitution and free elections. It is seen as a model for the region.
But its young democracy has also been tested by the rise of hardline Islamist movements, some of which have turned to violence. The army has been fighting a campaign against pockets of Islamist militants near the Algerian border.
State news agency TAP said gunmen raided houses for food in El Kef, a northeastern city about 160 km (100 miles) from the coast and 40 km from the Algerian border, before heading to the mountains that separate the two countries. TAP gave no further details.
Islamic State has claimed the Sousse attack. But officials say the gunman, named as Saif Rezgui, was not any watchlist of known potential militants. One source said he appeared to have been radicalised over the last six months by recruiters.
It was the second major attack in Tunisia this year, following an Islamist militant assault on the Bardo Museum in Tunis in March when gunmen killed a group of foreign visitors as they arrived by bus.
The tourism minister has described the Sousse attack as a catastrophe for the industry, which accounts for about seven percent of the country's gross domestic product.
"Germans, French and British officials informed us they would not prevent tourists from coming to Tunisia, but they want to participate in the investigation and to see clear security decisions," tourism minister, Salma Loumi, told reporters on Sunday.
"We will receive all ambassadors on Tuesday to inform them of all security measures taken to protect tourists," she said.
Loumi noted that many British tourists had decided to stay in Tunisia until the end of their holidays.
More than 3,000 tourists had already left the country a day after the attack.
"Tunisia is a beautiful country, and we will come back, but right now we need to leave, we need to forget what happened," said Lucy, a young British tourist leaving from a local airport near Sousse. "It's clear it is not safe here at the moment."
Islamist jihadists have attacked North African tourist sites before, seeing them as legitimate targets because they allow for a Western way of life and are tolerant of alcohol. Tunisia is one of the most secular countries in the Arab world.
Prime Minister Habib Essid said his government plans within a week to close down 80 mosques that remain outside state control, for inciting violence, and crack down on financing for certain associations, in order to counter jihadi rectruiters.
