Paris St-Germain say they will take “appropriate action” after Brazil striker Neymar failed to turn up for the first day of pre-season training.
The 27-year-old was due back at the club’s training ground on Monday.
The forward has been linked with a move back to former club Barcelona.
“Paris St-Germain notes that Neymar Jr was not in attendance at the agreed time and place. This was without the club’s prior authorisation,” read a statement.
“The club regrets this situation.”
In an interview with La Parisien, PSG’s sporting director Leonardo said: “Neymar can leave PSG, if there is an offer that suits everyone.”
He added that there had been “very superficial contact” from Barcelona.
“But to date, we do not know if anyone wants to buy it or at what price,” he added. “PSG wants to rely on players who want to stay and build something big.”
Brazilian media quoted Neymar’s father, Neymar Sr, as saying that PSG “were aware” that the forward was set to miss training on Monday because of charity commitments.
“The reason was known and planned for a year as part of his activities for the Neymar Institute,” he told Fox Sports Brazil.
“We couldn’t postpone them and he will return [to PSG] on 15 July.”
Neymar joined PSG from Barcelona for a world record 222m euros (£200m) in August 2017.
He has scored 34 goals in 37 league appearances to help them to consecutive Ligue 1 titles but also been involved in a number of disciplinary incidents, including being banned for three games for lashing out at a fan after PSG’s shock French Cup final defeat.
He will also miss the next three European matches for insulting officials.
The former Santos forward was stripped of the Brazilian captaincy in May before suffering an ankle ankle injury during an international friendly against Qatar last month that forced him to miss his country’s Copa America triumph on home soil.
Last week, Barcelona president Josep Bartomeu claimed that Neymar wants to leave PSG this summer.
According to reports in the Spanish media, Neymar has even offered to take a pay cut of 12m euros a year in order to facilitate a return to the Nou Camp, where he played between 2013 and 2017.
The Catalan side have already signed Frenkie de Jong from Ajax for an initial 75m euros (£67m) this summer and are thought to be interested in signing France forward Antoine Griezmann from Atletico Madrid.