Instagram has reportedly been blocked in China, amid fierce clashes between pro-democracy supporters and police in Hong Kong, The Independent reported Monday.
The photo and video-sharing service, which is owned by Facebook Inc, has been put on lockdown by police, according to various sources.
Instagram was blocked across China, including in Beijing and Shenzhen. It suggested that Facebook has also been limited.
The reports come as pro-democracy protesters, some wearing surgical masks and holding up umbrellas to protect against tear gas, expand their rallies throughout Hong Kong in protest against Beijing's decision to limit democratic reforms in the Asian financial hub.
Many of the photos have been labelled with the hashtag "Occupy Central," a phrase that was blocked on Sunday on Weibo, China's version of Twitter. It had been allowed earlier in the day.
China has called the protests illegal and endorsed the Hong Kong government's crackdown, but the social media blockade will not prevent users in Hong Kong from continuing to post on the site.