The United States is calling on the Vietnamese authorities to release one of its citizens who was caught up in a violent police crackdown on protestors who took to the streets across Vietnam this week.

Will Nguyen, 32, an American from Houston, Texas, who is currently studying in Singapore, was among those taken into custody on Sunday after he participated in a rare protest in Ho Chi Minh city. Video footage and witness accounts show Nguyen dragged through the streets by plain-clothed police, bleeding from a head injury.

Vietnam’s single-party communist state bans anti-government demonstrations and the authorities require approval for public gatherings. However on Sunday, protests erupted against the establishment of new economic zones, which some fear will open the country up to further Chinese investment and interests.

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The relationship between China and Vietnam has long been strained, but with the growth of Chinese influence across southeast Asia – mainly through infrastructure projects as part of their Belt and Road Initiative – and China’s increasing encroachment across the South China Sea, some Vietnamese have become fearful of their neighbour.

Nguyen was one of more than 100 arrested in the demonstrations, which also took place in Hanoi and central Vietnam’s Khanh Hoa and Binh Thuan provinces, where protestors faced tear gas and water cannon when they tried to storm the office of the People’s Committee.

There were multiple reports of assaults by the police as they broke up the protests and Brad Adams, Asia Director of Human Rights Watch, said: “With Vietnam’s poor record of handling protests, there’s every reason to believe that police are punishing dissent, not simply keeping public order.”

Will Nguyen (阮英惟） (@will_nguyen_) I can’t stress how enormous of an achievement this is for the #Vietnamese people. The communist government is allowing people to assemble peacefully and the people are exercising their civic duty to protest injustice. #Vietnam #Phandoidackhu

Nguyen is being held in jail, accused of “disturbing the peace”, but has not been charged.

Nguyen’s friends and family said Nguyen, who is of Vietnamese descent, was at the protest as an interested bystander and that he has no political agenda.

The protest coincided with him visiting Ho Chi Minh city to find a place to live once he finished a masters degree in Singapore.

A close friend of Nguyen’s, Mary-Alice Daniel, who is coordinating efforts to get him released, said: “Protest is unusual in Vietnam and Will was there because he really supported it as a display of civil participation.”

“He was there because he supported the Vietnamese people, he had no political agenda, it was not ideological. There is no evidence from people on the ground he was misbehaving in any way or doing anything other than peacefully protesting. But he was unlucky and he happened to be picked out from the crowd.”

Daniel does not believe the Vietnamese police knew that Nguyen was an American citizen.

Thi Thu Hang, spokeswoman for the ministry of foreign affairs denied that force had been used against Nguyen. US embassy spokesman Pope Thrower said that the embassy was aware of reports of the arrest but declined to comment further.

“When a US citizen is detained overseas, the US Department of State works to provide all appropriate consular assistance. Due to privacy considerations, we have no further comment.”

It is thought that more protests may take place this weekend. Last weekend’s rallies were also in protest against new cyber security laws, which require companies like Google and Facebook to store all data of Vietnam-based users in the country and open local offices.

It’s feared this could lead to more government censorship online. The Vietnamese authorities have already overseen the creation of a military cyber warfare unit, countering“wrongful views” online.