Protesters leave the Hong Kong Polytechnic University (PolyU) campus to surrender to police, in Hong Kong, China November 19, 2019. REUTERS/Athit Perawongmetha

GENEVA (Reuters) - The U.N. human rights office said on Tuesday that some Hong Kong demonstrators’ resorting to extreme violence, including against police, was “deeply regrettable and cannot be condoned” and voiced concern that the situation could deteriorate further.

Spokesman Rupert Colville urged Hong Kong authorities to de-escalate the situation at the Polytechnic University - where about 100 protesters are holed up - and address the humanitarian situation of those inside “which is clearly deteriorating”.

Hong Kong’s embattled leader Carrie Lam said on Tuesday she hoped the standoff between police and a group of anti-government protesters at the university could be resolved and she had told police to handle it humanely.