Hours after a prominent football journalist from the United States died while covering the ongoing FIFA world cup in Qatar, his brother alleged that he was killed.

Last month, Wahl said he was briefly detained by Qatari authorities for trying to enter a stadium wearing a rainbow shirt, in support of LGBT rights.

The 48-year-old journalist had on Monday written on his website that he had been unwell over the last 10 days and was taking antibiotics for suspected bronchitis.

Wahl collapsed during the Argentina-Netherlands match on Friday night. According to the BBC, a spokesperson for the Qatar agency handling the tournament’s management said the journalist received “immediate emergency medical treatment on site” and was transferred by ambulance to hospital. 

However, his brother Eric has uploaded a video alleging foul play. “My name is Eric Wahl and I am Grant Wahl's brother. I am gay and that's a reason he wore the rainbow shirt to the world cup. My brother was healthy. He told me he received threats. I do not believe my brother just died. I believe he was killed. I just beg for help.”

Wahl’s wife Céline Gounder said she was in “complete shock” and was “so thankful” for the support she had received from friends.

Meanwhile, the US Soccer Federation said it was “heartbroken". “Fans of soccer and journalism of the highest quality knew we could always count on Grant to deliver insightful and entertaining stories about our game, and its major protagonists.”

The supreme committee for delivery and legacy, the panel handling the tournament’s management in Qatar, said, “We are deeply saddened by the death of the US journalist Grant Wahl. Grant was known for his enormous love of football and was in Qatar to cover his eighth Fifa World Cup. He fell ill in the Lusail Stadium media tribune, during last night's quarter-final match between Argentina v Netherlands. He received immediate emergency medical treatment on site, which continued as he was transferred by ambulance to Hamad General Hospital. We are in touch with the US Embassy and relevant local authorities to ensure the process of repatriating the body is in accordance with the family's wishes."

BBC Sport’s Dan Roan tweeted, “Grant Wahl was a renowned and hugely respected journalist and the flood of tributes is testament to the esteem in which he was held.”

US tennis icon Billie Jean King called Wahl an “advocate for the LGBTQ community and a prominent voice for women’s soccer”.

This week, the journalist was given an award by Brazilian football icon Ronaldo for reporting on eight consecutive World Cups.

According to the BBC, FIFA president Gianni Infantino said Wahl’s love for football was “immense” and his reportage will be “missed by all who follow the global game”.