BEIJING (Reuters) - US President Barack Obama said on Monday the pro-democracy protests in Hong Kong were a complex issue and the primary US message was to make sure violence was avoided.

Short of denouncing China's handling of the crisis, Obama said the United States would not stop speaking out about human rights in China and the situation in Hong Kong because of US interests there.

"We don't expect China to follow an American model in every instance but we're going to continue to have concerns about human rights...Our primary message has been to make sure that violence is avoided," he said on a visit to Beijing.

Pro-democracy protesters in Hong Kong have occupied economically and politically important districts in the Chinese-controlled city for the past six weeks. Led by a restive generation of students, the protesters are demanding fully-democratic elections for the city's next chief executive in 2017, not the vote between pre-screened candidates that Beijing has said it will allow.

The peaceful protests, which China has said are illegal, drew well over 100,000 at their peak and are now concentrated in two key areas - the district of Admiralty next to government buildings and across the harbour in Mong Kok.

The standoff has grown in recent weeks between protesters and Hong Kong government officials with neither side backing down amid waning support from the Hong Kong public who are increasingly frustrated at gridlocked traffic around the financial city.

China has ruled Hong Kong through a "one country, two systems" formula since the former British colony returned to China in 1997. It allows wide-ranging autonomy and freedoms not enjoyed on the mainland and specifies universal suffrage as an eventual goal.