U.K. authorities are outlining a new set of counterterrorism measures, including a ban on insurance companies reimbursing ransom payments.

The bill to be outlined Monday by Home Secretary Theresa May reinforces Britain's long-held position that there should be no ransom payments to terrorists because payments to groups such as Islamic State merely place more people at risk.

May also wants to force Internet firms to retain data linking Internet Protocol or IP addresses to individual users.

The move comes as U.K. authorities warn of a rising threat of terrorism in Britain amid concerns that young people traveling to fight in Syria are becoming radicalized by the group. The fear is they will return and wage attacks at home.

Authorities estimate that some 500 British jihadists have traveled to Syria.