The two gunmen who killed 21 people in an attack on foreign tourists at a Tunis museum trained at a militant camp in Libya, Tunisia's secretary of state for security said.
"They left the country illegally last December for Libya and they were able to train with weapons there," Rafik Chelly told the private Al Hiwar Ettounsi television channel.
The gunmen were named by authorities as Yassine Abidi and Hatem Khachnaoui.
Mr Chelly said that Abidi had been arrested before making his way to Libya, without providing details.
Wednesday's attack on the National Bardo Museum in central Tunis was the country's worst since the 2011 uprising that toppled long-term ruler Zine El Abidine Ben Ali.
The security chief said the two gunmen had been "from sleeper cells" present in several areas.
"We know they can launch operations but we must piece together clues in order to conduct an arrest," Mr Chelly said last night.
He named locations of several suspected training camps for Tunisians in Libya, including the second city Benghazi and the coastal town of Derna, which has become a stronghold for jihadists.
Authorities say as many as 3,000 Tunisians have gone to Iraq, Syria and Libya to fight in jihadist ranks, raising fears of battle-hardened militants returning home to plot attacks.
Honeymoon couple hid in storeroom during attack
A Spanish man and his four-month pregnant wife hid in a storeroom overnight during the attack.
The couple were on their honeymoon in Tunisia after getting married earlier in March when they got caught up in the attack on tourists at the National Bardo Museum in Tunis, relatives said.
"As we came out of the museum, we saw that they were shooting at people around the entrance. One person was killed and we realised what was happening so we went to hide," Juan Carlos Sanchez said in a brief interview with Spanish national television.
"We hid in a storeroom and stayed there, listening to everything that was happening and waiting for it to be over," Sanchez said.
Tunisian officials said that a museum employee helped the couple to hide during Wednesday's attack and the three laid low all night before being found yesterday.
Mr Sanchez, from near Valencia in eastern Spain, appeared alongside his wife Cristina Rubio in images taken shortly after they were brought out of the museum.
Hospital sources in Tunis said that Ms Rubio had been examined, and that she and her husband were in good health despite being in shock.
Another Spanish couple, Antoni Cirera and Dolors Sanchez from Barcelona, were killed in the attack, Spain's foreign minister Jose Manuel Garcia-Margallo said.
Spain was sending a military aeroplane to Tunisia to return their bodies to Barcelona later today, officials said.
Attack victims identified
ITALY - Four Italians were killed, according to Tunis and the foreign ministry in Rome, which said six others were wounded.
JAPAN - Tunisia said three Japanese died, a figure confirmed by Prime Minister Shinzo Abe, who added that another three were wounded.
FRANCE - According to the Tunis authorities, three French tourists were among the dead.
France has confirmed the death of two of them, while President Francois Hollande said there was a possibility of a third casualty.
Both fatalities confirmed by Paris came from southern France, with local authorities saying one was a retired man and the other the manager of a racecourse.
COLOMBIA/AUSTRALIA - Tunis reported that one Colombian and a Colombian-Australian were killed.
The foreign ministry in Bogota said they were Miriam Martinez, 56, and her son Javier, 28, who also had Australian nationality and lived in Sydney.
The father, retired army general Jose Arturo Camelo, survived.
The family had gone on a cruise to celebrate the son's graduation.
SPAIN - Tunisia and Spain have both reported that two Spaniards were killed. Madrid named them as Antoni Cirera and Dolors Sanchez from Barcelona and said they had been on a cruise.
BRITAIN - A British tourist was among those killed, London and Tunis said.
Officials named her as Sally Adey and said she was visiting the museum with her husband, who survived.
BELGIUM - A Belgian woman was killed, said Tunis and Brussels, which added that the victim's husband was wounded in the knee.
POLAND - Tunisian officials said a Polish tourist was killed.
TUNISIA - Officials say a Tunisian policeman was among the victims.
Tunisia's health ministry said three victims of the attack remain to be identified.
