Three suspected members of Islamic State’s Afghan branch, Islamic State Khorasan, have been charged in Belgium with planning a terrorist attack. Police released four other people who had also been detained during searches of houses across the country on Thursday, three of them after being questioned by an investigative judge, the state prosecutor’s office said. Prosecutors said all seven people taken into custody in the Brussels region and in cities including Antwerp, Liège and Ghent were natives of Chechnya, with the three who were charged suspected to be members of Islamic State Khorasan. Prosecutors said on Friday there was no indication that the suspects had chosen a specific target. They declined to give further information. Belgian media had reported that investigators did not want to take any risks so close to the Olympic Games in Paris. The prosecutor’s office did not respond to a question about a possible connection to the Games, which had its opening ceremony on Friday evening. The French anti-terrorism prosecutor said no arrests or searches occurred in France as part of the investigation, but did not say whether French authorities were involved in it. The 2015 Paris terrorism attacks, in which 130 people were killed and 368 wounded, were largely planned and coordinated from neighbouring Belgium, and several of the attackers were Belgian nationals or residents. The following year, bombings at Brussels airport killed 34 people and injured 340. Among those convicted for the attacks was Salah Abdeslam, who was also the main suspect in the Paris attacks trial.