Police have intensified a campaign against candid photography, and acts of obscenity, on the Shanghai metro as the hot summer approaches.

Reinforced electronic surveillance and stepped-up patrols in the subway carriages and stations will be carried out.

A 24-year-old man was held in administrative detention by police on Monday after he tried to photograph a woman with his mobile phone.

Four cases of indecency and two cases involving intimate pictures of women have been investigated this year, statistics from the police showed.

Those who molest or expose their bodies in public will face being detained by the police.