LONDON (AP) — British police say they have arrested a seventh person over an alleged plot to launch a terrorist attack.

The Metropolitan Police says the 22-year-old woman was arrested Saturday at a home in east London “on suspicion of the commission, preparation or instigation of acts of terrorism.”

Six other people were arrested on the same charges Thursday, including a British Muslim convert and three brothers who were detained by armed police at their home close to London’s Olympic Park.

Counter-terror officers are on high alert ahead of the Summer Games, which begin July 27, but police say this week’s arrests are not connected to the Olympics.

Britain’s terrorist threat risk remains at substantial, the middle point on a five-point scale, meaning an attack is a strong possibility.