A$AP Rocky rose out of poverty in Harlem to become one of hip hop's biggest stars. (Photo: AFP)

US rapper A$AP Rocky pleaded not guilty to assault at his trial in Sweden Tuesday over a street brawl, saying he acted in self-defense in a case that has stirred diplomatic tensions and outraged fans.

The 30-year-old rapper, whose real name is Rakim Mayers, was arrested on July 3 along with three other people following the fight in Stockholm on June 30. One of them, the rapper's bodyguard, was later released.

At the start of Tuesday's trial, prosecutor Daniel Suneson alleged that Mayers and two other accused had assaulted the 19-year-old male plaintiff.

Suneson said the accused had punched, kicked, and hit the plaintiff with a bottle.

He showed the court parts from some 550 pages of the preliminary investigation, including surveillance footage and maps to establish a timeline of the events leading up to the brawl.

The prosecution also showed photos detailing the alleged victim's injuries, which included bruises and cuts, seemingly from the glass.

- Video evidence -

Much of the trial's first day centered on the analysis of video evidence.

The prosecution laid out its case by showing a number of videos, including one published by US celebrity news outlet TMZ, where the rapper can be seen throwing a young man to the ground and then aiming several punches at him while he is down.

The court also saw videos posted to the rapper's Instagram account, in which the young man can be seen arguing with the musician over a pair of headphones.

The artist appears to repeatedly ask the man and his friend to stop following him and his entourage. One of the young men can also be seen hitting the artist's bodyguard.

The evidence also included videos retrieved from the phones of members of the artist's entourage, as well as 13 minutes of security footage from a fast-food restaurant.

Suneson told the court they proved that the videos posted to the artist's Instagram had been edited to remove instances where the bodyguard grabbed and pushed the plaintiff prior to the fight.

The prosecutor also showed text conversations between members of the artist's crew, stating that the video uploaded to Instagram had been "cleaned up a bit".

In later testimony, the plaintiff said he had only asked the artist's entourage if they had seen his friend when he was first pushed by the bodyguard, adding that this is why he did not leave when asked.

"He pushed me, and I wanted to know why," he told the court in Persian as the Afghan-born man lived in Iran prior to moving to Sweden.

During the scuffle with the bodyguard, the man's headphones broke and he said that was his reason for following the group as they first left the restaurant.

According to his testimony, he was later hit in the back of his head with a bottle before being thrown by Mayers.

- 'Deeply provoking behavior' -

Mayers kept his cool throughout the proceeding, smiling and waving at his mother, who was seated on the front row of the courtroom visitor's bench, as he entered and left.

He sat with his arms crossed as his lawyer Slobodan Jovicic argued that the rapper's actions were the result of the plaintiff and his friend showing "a threatening, aggressive and deeply provoking behavior".

"He admits that he threw the plaintiff on the ground, that he stepped on his arm and punched or pushed his shoulder," Jovicic told the court, saying it was a case of "self-defense".

Jovicic also spent a lot of time re-examining the videos and crime scene photos to show that Mayers could not have used a bottle since he can be seen holding the plaintiff in the video as you hear a glass bottle shatter -- the only one found at the scene.

He stressed that the videos showed that his client and his entourage repeatedly told the plaintiff that they had "peaceful intentions and did not want an incident".

The trial is scheduled to resume on Thursday when the court will hear Mayers' own testimony.

- Diplomatic tension -

On July 5, the Stockholm District Court ordered that Mayers be kept in custody while the case was being investigated as he was considered a "flight risk".

Fans, fellow artists and US Congress members have been campaigning for his release.

An online petition called #JusticeForRocky has garnered more than 630,000 signatures. Social media campaigns have urged fans to boycott Swedish brands such as IKEA.

US President Donald Trump has repeatedly called for the rapper to be freed, drawing complaints of interference from Swedish politicians.

Robert C. O'Brien, US Special Presidential Envoy for Hostage Affairs, had been sent to attend the trial.

"The president asked me to come here and support these American citizens and we're working to bring them back as soon as possible," O'Brien told AFP, declining to comment on what he thought of the prosecution's case.