The Tunisian jihadist behind last month's massacre of foreigners at a seaside resort had previously worked in tourism, officials said Sunday, as his mother insisted the young man was "brainwashed."

In an interview on Sunday, Prime Minister Habib Essid revealed more details about 23-year-old Seifeddine Rezgui, who gunned down 38 foreign tourists in the June 26 attack.

He was dressed like a tourist, but his intentions were deadly. Witnesses said Sunday the gunman who mowed town tourists at a Tunisian beach smiled as he pulled the trigger.

Armed with a Kalashnikov assault rifle, the man who massacred 38 people at a popular beach resort on Friday embarked on a murderous rampage witnesses say lasted more than 40 minutes.

Six people remained in "serious condition" in hospital on Sunday two days after a mass shooting at a beachside hotel in Tunisia that left 38 people dead, the hotel's Spanish management said.

"The hotel management is in permanent contact with local hospitals checking on the condition of the wounded who are still hospitalized," the RIU group, which runs the Riu Imperial Marhaba Hotel, said in a statement.

Thousands of scared foreign holidaymakers were being flown from Tunisia on Saturday after an Islamist gunman killed 38 people, most of them British tourists, at a beach resort.

The Islamic State jihadist group, which controls swathes of Iraq and Syria, claimed responsibility for the attack, the deadliest in Tunisia's recent history.

A man pulled a gun hidden in a beach umbrella and opened fire at a packed Tunisian holiday resort Friday, massacring 37 people in the country's worst attack in recent history.

The carnage at the popular Mediterranean resort of Port el Kantaoui came the same day as a suicide bomber killed 25 people at a Shiite mosque in Kuwait and a suspected Islamist attacked a factory in France.

A suicide bomber blew himself on Wednesday on a beach in Tunisia's resort town of Sousse while security forces foiled another planned attack nearby, the interior ministry said.

"A man blew himself up on a beach in Sousse," ministry spokesman Mohamed Ali Laroui told Agence France Presse, adding that no one else was killed.