Police in Vietnam have arrested seven people over the "terrorist" bombing of a police station in Ho Chi Minh City last month that injured three people, police said on Thursday.
The incident, in which two small explosive devices were detonated, followed protests by thousands of people in several cities against government plans to lease new economic zones to foreign investors.
"This is a terrorist case against the people's government," Ho Chi Minh City police said in a statement on their official website.
"The police arrested seven people and seized 10 kg of explosives."
Four of those arrested face "terrorist" charges, and three have been charged with trading in explosives, they added.
Police seized eight more bombs, they said. Pictures alongside the statement showed confiscated bomb-making materials and ammunition, they added.
The nationwide protests were sparked by concerns that plans to develop economic zones by offering land leases for up to 99 years would be dominated by investors from neighboring China, with which Vietnam has a history of fractious ties.
Despite sweeping economic reforms, communist-ruled Vietnam tolerates little dissent, and has described some anti-government groups as "terrorists," a charge punishable by death.
In December 2017, Vietnam jailed 15 people it said were guilty of plotting to bomb its largest airport, in Ho Chi Minh City.
They received money from the California-based Provisional Government of Vietnam, a group still loyal to the now defunct state of South Vietnam, which Hanoi listed as a "terrorist" organization in January.
A U.S. embassy spokesman said at the time the group was not designated a terrorist outfit by the U.S. State Department.
Police did not identify a group behind the police station bombing on June 20, but said on Thursday it had been carried out "under the direction of overseas reactionary organizations" and the perpetrators had trained online.
The group had been working for a "resistance organization in the United States," the VnExpress news website said, citing police.