The match between Jönköpings Södra and Östersund was approaching full-time when a masked black-clad supporter burst onto the pitch and assaulted Östersund keeper Aly Keita.

Keita was chased and struck before players and security officials intervened and arrested the attacker.

The keeper was seen clutching his head as he returned to the changing rooms where he was tended to by medics, with the referee stopping the game which had been heading towards a 1-1 draw.

When questioned by the police the boy said he had no connection to either of the teams and had acted out of desperation when it became apparent that he was going to lose money on his bet, local news site Jmini reports. 

He also told police that he had left a bomb in his bag at the stadium, though that proved to be untrue. 

The 17-year-old attacker had made the 300-kilometre trip to Jönköping from his home town of Södertälje, in eastern Sweden.

The boy claims he bet between 5,000 and 10,000 kronor ($1,200) on the game, according to prosecutor Pernilla Törsleff.

“Whether or not the police or I, as a prosecutor, consider it credible is immaterial. It’s all about what we can show,” she told Jmini. 

The 17-year-old suspect has close family ties to the notorious Södertälje mafia, according to a TV4 report. 

Sweden’s state-run gambling operator Svenska Spel launched an investigation into suspected match-fixing after the game was abandoned, but said it had not seen any unusual betting patterns. 

Legal experts and football fans have however speculated that exceptionally high bets would likely be placed overseas, for example with Asian gambling syndicates, to avoid detection by Swedish authorities.

Prosecutors do not have any other suspects in the case and expect to complete the preliminary investigation in two to three weeks.