Determined queues formed before dawn in front of the club shop on the Champs- Elysees while raucous crowds gathered outside the Parc des Princes stadium on Wednesday as Lionel Messi was officially unveiled as a Paris Saint-Germain player.

And the verdict?

"It's been a mental morning," a staff member of the club store at the Parc des Princes told AFP.

"It's the first time we've ever seen this," he said after PSG shirts with 'Messi' and the number 30 emblazoned on the back were snapped up by hundreds of fans.

Costing 87 euros ($102) for children, 108 euros ($126) for women and 158 euros (185) for men, the cash registers went into overdrive.

That was just as well as Messi is reportedly being paid 35 million euros ($41 million) a year by the club's Qatari owners.

Club president Nasser al-Khelaifi introduced Messi on a live-streamed broadcast which was also shown on a giant screen outside the ground, offering shop staff a chance to restock.

"I'm very proud to present Leo Messi as a PSG player," said the club president.

"It is an amazing and historic day for the club, for the football world."

Paris Saint-Germain's Argentinian forward Lionel Messi salutes supporters gathered outside the Parc des Princes stadium
Paris Saint-Germain's Argentinian forward Lionel Messi salutes supporters gathered outside the Parc des Princes stadium AFP / Bertrand GUAY

Fans at the PSG stadium chanted Messi's name as the Argentine held up the shirt with his name and the number 30 on it, which will surely become as iconic the world over as was his 10 at Barcelona.

When Zlatan Ibrahimovic signed for PSG in 2012 there was a glitzy unveiling in front of the Eiffel Tower, but the discreet Messi, in his immaculate suit, was simply photographed on the pitch.

"I've been a fan of PSG for over 30 years and we've been through it all," said Mohamed, a 49-year-old fan in the queue in front of the stadium.

"Twelve years ago we were fighting relegation; now we'll be playing a front line of Neymar-Mbappe-Messi."

Djibril, 23, was in similar awe.

"I'm a PSG fan and if I had to queue up all day for a Messi shirt then I will," he said.

As the morning advanced fans got rowdier and some groups set off fireworks that led to a child being injured. Police arrested one fan.

When Messi himself arrived at the Parc des Princes a cry of 'Messi, Messi, Messi' went up as a forest of mobile phones were held aloft to record the moment.

Another PSG fan, Wesley said he felt compelled to bring along his two children aged 7 and 9, for the momentous occasion.

"I had to bring them, I hope they will it remember for a long time, because Messi being here in Paris is just mental," he said.