British citizens who go to designated conflict zones could face up to a decade in prison under a new law.

The Counter-Terrorism and Border Security Act 2019 is meant to address the threat of individuals who go overseas to take part in fighting. The measure won't allow prosecutions retrospectively, so those who fought with the so-called Islamic State group are exempt.

The law enacted Friday will allow exceptions for journalists, aid workers and others with a good reason, such as people who want to attend a funeral.

Home Secretary Sajid Javid says the law gives "police the powers they need to disrupt terrorist plots earlier and ensure that those who seek to do us harm face just punishment."