Updated

Media freedom campaigners say police in Zimbabwe are breaking the law by seizing and banning small radio receivers that can tune in to stations not linked to the state broadcasting monopoly controlled by President Robert Mugabe's party.

The Media Institute of Southern Africa said Friday no regulations outlaw the hand-cranked, solar powered radios that democracy and election support groups plan to use ahead of a referendum on a new constitution next month and crucial elections later in the year.

Police insist the radios and cheap Chinese 3G smartphones are being supplied by "subversive organizations" and pose a security threat surrounding the polling.

MISA said any broadcast receiver only requires a routine listeners' license. The police action was a grave threat to active and informed participation in upcoming voting, it said.