HANOI (Reuters) - Police in Vietnam’s Ho Chi Minh City on Friday issued a prosecution order for an American man of Vietnamese descent for his alleged involvement in a protest over government plans for economic zones last week, state media reported.

William Anh Nguyen, born in 1985, was one of thousands of people who protested on Sunday against a draft law to develop economic zones under which land leases of up to 99 years will be offered to investors.

Protesters fear the leases may be snapped up by investors from powerful neighbor China, with which Vietnam has a rocky history.

Nguyen was “gathering and causing trouble” in Ho Chi Minh City and was filmed on camera urging others to climb over barricades, the state-run Vietnam News Agency reported.

A U.S. State Department official said the State Department has raised concerns and engaged with Vietnamese authorities on the matter and that the Vietnamese government permitted consular access to Nguyen on Friday.

The official said they were deeply concerned by reports that Nguyen was injured on Sunday at the time he was taken into custody by Vietnamese authorities and that they would continue to push for continued and regular access to Nguyen.

Video footage of Nguyen shared on social media showed he had blood on his head during the protest. Vietnam’s Foreign Ministry spokeswoman Le Thi Thu Hang denied any use of force against Nguyen during a news conference on Thursday.

Ho Chi Minh police said on their website on Friday that they were dealing with 310 people over the protests and that seven of them were criminal cases. It was unclear if Nguyen was one of the seven.

They said initial investigations showed there were signs of political opponents and reactionary groups having incited people to protest and destabilize the security and political situation.

The protests have come at a time of rising tensions over the disputed South China Sea, nearly all of which is claimed by China.

Vietnam is one of several countries in the region that have claims in the South China Sea, through which an estimated $5 trillion in trade passes each year.