A man who touched a woman's breast on the Shanghai metro surrendered to police and is under administrative detention, Shanghai Morning Post reported on Tuesday.

A video clip on the Internet showed the 36-year-old man, surnamed Ling, harassed a female passenger who sat beside him on metro line 2 during morning peak hour on June 6.

Thirteen cases of indecency and taking intimate pictures of women in subway carriages and stations have been dealt with this year and the number is climbing as the heat of summer increases, police said.

Police have intensified a campaign against acts of obscenity and candid photography and have plainclothes officers patrolling at stations.

Every passenger has four pictures taken from the front when entering metro stations by surveillance cameras and the police can find any suspect easily with surveillance tapes, according to police.