The president of Serbia has said Real Madrid forward Luka Jovic faces arrest if he fails to observe his coronavirus self-isolation.

Jovic, 22, has been the subject of fierce criticism in Serbia after flying home last Thursday, with the permission of Real Madrid's medical department.

He has since been seen out in Belgrade, as has fellow player Nikola Ninkovic of Serie B side Ascoli.

"One of them [Ninkovic] is in a hotel and the other [Jovic] is in his apartment" Serbian president Aleksandar Vucic said in a news conference on Thursday evening.

"If either of them leaves those places, they will be arrested. I think the two of them regret what they have done, but I'll make it clear to them that people's lives are much more important than their millions. Despite all that, we're not going to crucify anyone."

Real Madrid's doctors had told Jovic he could continue his self-isolation -- implemented for all of the club's footballers after a basketball player tested positive for COVID-19 last week, leading to the closure of their Valdebebas training complex -- at home in Belgrade.

The striker has scored just two La Liga goals since joining Real Madrid for €60 million from Eintracht Frankfurt last summer.

His morale is low, and ESPN has been told that that -- along with a muscular problem suffered in recent weeks -- led Real Madrid's doctors to believe a return to Serbia might be beneficial.

Jovic has apologised for his actions and claimed he did not receive proper advice.

"While in Spain, I tested negative for coronavirus, and I decided to travel to Serbia to help and support our people and be close to my family, in agreement with my club," he said in a post on Instagram.

"When I landed in Serbia, I again tested negative for coronavirus. I am very sorry that some people did their job unprofessionally and did not give me the correct instructions on how to behave in self-isolation."

He continued: "In Spain, I was allowed to go to a pharmacy and a supermarket so I could get the groceries I needed, which is not the case here.

"I apologise to everyone if I have endangered them in some way and I hope that together we can manage to overcome all this."