The bus bombing that killed at least 12 people in Tunisia’s capital was carried out using 10 kilos of explosives in either a vest or a rucksack.

The bus bombing that killed at least 12 people in Tunisia's capital was carried out using 10 kilos of explosives in either a vest or a rucksack, the interior ministry said Wednesday.

"The terrorist attack was committed using a backpack or vest containing 10 kilos of explosives," a ministry statement said, without specifying whether it was a suicide bombing.

It said the 12 presidential guards killed in the attack on their bus in Tunis on Tuesday had been identified based on their fingerprints.

"The 13th body is believed to be that of the terrorist who caused the explosion," the ministry said, adding that DNA tests were being carried out to try to identify the suspected attacker.

The authorities imposed a nationwide state of emergency and a 9:00 pm to 5:00 am curfew in the capital following the bombing, the latest attack in a country plagued by terrorist violence.