STOCKHOLM (Reuters) - Swedish prosecutors on Friday extended American rapper A$AP Rocky’s detention by six days amid their ongoing investigation into a street fight in Stockholm as U.S. President Donald Trump said he planned to call Sweden’s prime minister about the case.

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A district court agreed to a request from prosecutors for more time for their investigation of alleged aggravated assault by the 30-year-old performer, producer and model, whose real name is Rakim Mayers.

“The court decided that the artist will remain in custody until July 25 because of the flight risk,” Daniel Suneson, the prosecutor in charge of the case, said in a statement. “This gives us time to complete the investigation.”

The artist’s lawyer, Slobodan Jovicic, said the decision was expected but unfair, and that A$AP Rocky is innocent.

“He (Mayers) believes he was assaulted and has acted in self-defence,” Jovicic told journalists.

The detention of Mayers, who attended the court dressed in a green T-shirt, has gained widespread attention including from Trump and U.S. first lady Melania Trump. More than 600,000 people have signed an online petition for his release, while fellow artists have expressed their support.

Trump said on Twitter he spoke with rapper Kanye West about the case on Friday and would be calling Swedish Prime Minister Stefan Lofven “to see what we can do about helping A$AP Rocky.”

“So many people would like to see this quickly resolved!” Trump added.

West’s wife, reality TV star Kim Kardashian West, in a tweet on Thursday thanked Trump, U.S. Secretary of State Mike Pompeo and White House adviser and Trump son-in-law Jared Kushner for trying to get Mayers released.

Kardashian West has worked with the Trump administration on criminal justice reform.

Trump told reporters on Friday he did not know Mayers but that “many members of the African-American community” sought his help for the rapper, who is black.

U.S. Representative Adriano Espaillat of New York, where Mayers was born, has also urged his release.

Mayers was detained on July 3 along with his bodyguard and two other members of his entourage in connection with a fight in a Stockholm city-centre street in the early hours of June 30. The performer was in Stockholm for a concert, and has had to cancel several shows in his European tour.

U.S. Assistant Secretary of State for Consular Affairs Carl Risch met with Mayers on Friday, and was due to discuss the issue with the foreign ministry and the justice department during a two-day visit to Sweden.

Before his arrest, Mayers uploaded videos to his Instagram account of an altercation with two men, saying they had followed him and his entourage and that he had not wanted any trouble. The bodyguard was released without charge while a judge on July 5 extended the detention of Mayers and his two other associates.