Researchers claim a new study provides some of the most compelling evidence yet for tighter gun controls in the US.

The team followed the consequences of the State of Missouri repealing its permit-to-purchase handgun law in 2007.

The law had required purchasers to be vetted by the local sheriff and to receive a licence before buying a gun.

Reporting soon in the Journal of Urban Health, the researchers will say that the repeal resulted in an immediate spike in
gun violence and murders.