Benedict Rogers, East Asia Team Leader at Christian Solidarity Worldwide, has condemned the "dangerous" refusal of Hong Kong and Beijing to engage with protesters in the face of an increasingly volatile situation in the city.
Writing in UCA News, Mr Rogers said he feared a "Tiananmen-style crackdown" on pro-democracy protesters after China reportedly started amassing troops at the border of the semiautonomous region and its Hong Kong garrison issued a video, widely seen as a warning, showing troops engaged in "anti-riot" drills.
"Hong Kong has gone from peaceful marching demonstrations to being at risk of becoming the West Bank or West Belfast within the blink of an eye," he wrote.
"There is a massive, unprecedented failure of governance in Hong Kong. All of this heightened tension could easily have been avoided.
"Hong Kong people are pragmatists, not radicals. Even the young demonstrators who stormed the Legislative Council last month protected books and antiques as they made their protest against the establishment.
"It would not take much to calm the situation, yet the intransigence of the Hong Kong and Beijing authorities is staggering — and dangerous."
He warned that a crackdown similar to that carried out on the student-led protests of 1989 in Beijing's Tiananmen Square could be repeated with devastating consequences in Hong Kong.
"There are, in reality, only two ways to resolve the impasse in Hong Kong right now. One is, God forbid, a Tiananmen-style crackdown, which we are already beginning to see in embryo with the police's widespread use of teargas, batons, beatings, shotgun triggers pulled, and Triad gangsters mobilized," he said.
"Let us hope that neither [President] Xi Jinping nor [Hong Kong Chief Executive] Carrie Lam allows for the deployment of the trigger-happy [People's Liberation Army] PLA, which would result in a massacre that would not only slaughter the individuals concerned — hundreds of them — but kill off the hopes of Hong Kong remaining an international financial center and an open city in the region.
"Such a massacre would be the slaughter of Hong Kong itself, it's very raison d'etre, its meaning, soul and being."
Hong Kong has been the scene of protests for two months, with hundreds of thousands of people marching through the streets against the draft Extradition Bill that would see some suspected criminals sent to the mainland for trial.
Ms Lam has called the Bill "dead" in the wake of the protests but has stopped short of withdrawing it completely - a demand of the protesters.
Mr Rogers called the piece of legislation "absurd" and "ill-thoughtout", and said that the only way to end the protests without a violent crackdown was for Beijing and Hong Kong to allow for some democratic reforms.
He said that there was hope for a breakthrough if the people of Hong Kong people could be persuaded that their elected legislators would represent them and "listen to them".
"If Hong Kong people feel they have some say in their future, then they will — provided they are confident of the assurances — get off the streets, re-engage with the political system and restore calm and order and, crucially, confidence to Hong Kong's battered economic reputation. Hong Kongers are not, by nature, extremists," he said.
At the same time, he said the protesters needed to embrace non-violent means to express their dissatisfaction.
"But unless there is a move in the direction of democratic reform by the authorities, and a move in the direction of dialogue and non-violence by the protesters, Hong Kong is heading for bloodshed, turmoil and tragedy on a scale it has not yet seen," he said.
The call for non-violence has been repeatedly made by Church leaders in the city. The Anglican Bishop of Hong Kong Paul Kwong has written to parishioners urging them to resist violence in all its forms and embrace peace in the midst of the "turmoil" affecting the city.
"In the past week, we have seen that Hong Kong has reached a tipping point. The situation is really worrying because the level of violence is escalating. We reiterate our opposition to all forms of violence," he said in the letter, issued to parishioners in Chinese.
"We say 'no' to violence, including violent language, spiritual violence, the violent exercise of power, and physical violence. We must learn to release our hearts from the slavery of sin. We can freely, joyfully, lovingly, with peace and hope, and for the great purpose of all, strive for the establishment of Heaven in this world."
He added: "Today, let us rebuild Hong Kong through the grace of the cross, making her a 'Pearl of the Orient' that can shine the glory of Christ and the radiance of humanity."
The protests began peacefully but the violence escalated to alarming levels when a mob - suspected to be Triad gangsters - attacked protesters at the Yuen Long MTR station.
Although the protests started out against the extradition bill, it has evolved into wider protests about encroachments on Hong Kong's democracy and police corruption.
The police have faced widespread criticism for their use of teargas and rubber bullets against protesters, and for failing to act quickly enough when the Yuen Long attack unfolded, arriving on the scene only after the attackers had fled. The Independent Commission Against Corruption (ICAC) has launched an investigation into potential misconduct by police officers.
The Vine Church, an English-speaking international church in the Wan Chai district of Hong Kong, has voiced alarm at the "emotional stress" being experienced by the people of Hong Kong.
It has urged people suffering from anxiety or depression in light of the protests to seek professional help or reach out to the church for support.
"We were shocked by the acts of violence that took place last Sunday night in Yuen Long. This and other recent events have left many in our city and our church experiencing high emotional stress including fear and anxiety, anger, feelings of hopelessness, worries about our future and sleep difficulties," it said in a Facebook update.
"To date, five people have died by suicide related to the current situation. As a community, we must be able to talk about this openly and honestly so that we can be a safe place for care and support.
"If you are experiencing emotional distress, please reach out to someone you trust, get in touch with us, or speak to a medical/mental health professional (doctor/GP, counsellor etc.).
"Let's also all reach out to support one another at this time. If you or someone you know are having thoughts of self-harm or suicide, there are people who want to hear you and talk with you."
It added: "As a body, let's continue to hold each other up during these challenging times."
If you have been affected by any of the issues in this story and need support, the Vine Church can be contacted at firstname.lastname@example.org
The Hong Kong branch of The Samaritans can be reached 24 hours at 2896 0000 (multilingual). The Suicide Prevention Centre offers a 24-hour Cantonese-language helpline at 2382 0000.