"We have identified more people in different areas that we were not aware of", said Vivian Tan, a spokeswoman for UNHCR, while adding that there could be some double-counting.
The violence and exodus began on August 25 when Rohingya insurgents attacked Myanmar police and paramilitary posts in what they said was an effort to protect their ethnic minority from persecution by security forces in the majority Buddhist country.
The protest in Hong Kong would bring together several local Muslim as well as Catholic and other Christian associations under an umbrella group named the Hong Kong Working Group Against Rohingya Genocide, he said.
This is published unedited from the IANS feed. Noting India's obligations under worldwide law, he said: "India can not carry out collective expulsions, or return people to a place where they risk torture or other serious violations".
He further asked the Myanmar government to stop claiming the Rohingyas were setting fire to their own homes and laying waste to their villages.
View of a burnt house following violence in in Maungdaw township in Rakhine State in Myanmar, September 6, 2017.
United Nations workers on the Bangladesh side of the border say about 294,000 Rohingya civilians have arrived over the past two weeks, while tens of thousands more are on the move within Rakhine without adequate food or shelter.
Myanmar says its security forces are carrying out clearance operations to defend against ARSA, which the government has declared a terrorist organisation.
The Indian Ministry of External Affairs has urged Myanmar that the situation in Rakhine state due to outflow of Rohingya Muslims be handled with restraint and maturity. They wait on the Myanmar border to take fishing boats to Bangladesh.
Protesters were holding placards and were chanting slogans against Burmese government and military for carrying out worst human right abuses against the Muslim community.
Speaking to reporters before his departure for Astana, Kazakhstan, for an global conference, the president called for pressure on the Myanmar government and Army to protect Rohingya civilians.