Security concerns have been raised about the imminent release from prison of the radical preacher Anjem Choudary and other supporters of the banned extremist group al-Muhajiroun.
About a dozen followers are out or will be soon, as restrictive terror protection orders on others end.
A counter-terrorism activist says the group could become active again.
Security Minister Ben Wallace told BBC News the government works to reduce the risk of freed terrorist offenders.
He said there are a "suite of powers and measures we can put in place," adding: "Terrorist offenders have a lot more supervision than normal offenders and that's because we recognise the risk and we seek to reduce it to as low as possible."