On Friday Habib Essid took part in a minute’s silence to remember the 38 people who were killed in the town of Sousse, south of Tunis, a week ago.
At the beach in Sousse where the tourists’ blood was spilled, Britain’s ambassador Hamish Cowell was among those honouring all 38 victims of last week’s massacre, laying a wreath at the site.
Today’s silence was marked at ceremonies all across the UK.
The Queen, who was at the University of Strathclyde in Glasgow, and Prime Minister David Cameron, who was in his constituency in Oxfordshire, joined millions of people across Britain as Big Ben chimed midday.
Across Britain, the silence will be observed at noon to remember all the victims, and flags will be flown at half-mast over Whitehall departments and Buckingham Palace.
Formula One teams will also fall silent at Silverstone ahead of this weekend’s British Grand Prix while players from Australia and Essex will observe the silence during the tour match in Chelmsford.
Councils including Cardiff, Caerphilly and Rhondda Cynon Taff also held a silence, and flags on authority buildings flown at half mast.
Tunisia’s prime minister has told the BBC that the slow response of police to last week’s deadly attack on a tourist resort was a major problem.
Outside Buckingham Palace hundreds of people gathered along the gates and lined the pavements for the occasion, before a brass band marched out of the main gates.
The moment of remembrance for the attack claimed by the Islamic State group comes a day after the British government raised the possibility of extending air strikes against IS militant from Iraq to Syria.
The Muslim Council of Britain has urged British Muslims to make their voices heard to pray for peace, and speak out against terrorism, and has called on mosques and imams to deliver a sermon of peace at Friday prayers, to remind people “that these killers do not respect the sanctity of life as laid down in Islam”.
It is believed Rezgui – who was shot dead by police – had accomplices who helped him to carry out the atrocity.
Three Irish nationals, two Germans, one Belgian, one Portuguese and one Russian were also among the dead.
Tunisia is now holding eight suspects in custody over direct links to the gunman.
The bodies of 25 of the British victims have now been repatriated on a military transport plane to Royal Air Force base Brize Norton.
The remains will be released to the families following post-mortem examinations.
The first inquest for a British victim of the attacks opened Friday at a London court.