Tran Thi Hong, the spouse of Nguyen Cong Chinh, was interrogated on three seperate occasions last week by police and officials over issues including her "illegal" faith, Christians Solidarity Worldwide has said.
Ms Hong was reportedly pinned to the ground, pinched and had chopsticks forced in her mouth during the meetings, while her 18-year-old son was violently choked, bound and arrested after trying to intervene.
Her question comes after Ms Hong said last month she had been severely beaten and abducted by security agents in Gia Lai province when she tried to hold a meeting with the US Ambassador At Large on International Religious Freedom on March, 31.
Mrs Hong was reportedly forced to sign a statement which wrongly said the police had not tried to prevent her from meeting David N. Saperstein.
CSW's Chief Executive Mervyn Thomas said: "We condemn the torture, ill-treatment and harassment of Tran Thi Hong and her family by the Vietnamese authorities.
"Rather than apologising and compensating Mrs Hong for the injuries she sustained on 14 April, the authorities have continued to harass her family, interrogate and detain her against her will, and use physical abuse to try to force her to sign a false statement of guilt.
"We call on the authorities to cease all harassment of Mrs Hong and her family, to investigate immediately and impartially reports of torture in custody, and to uphold the right of Mrs Hong and her family to practice their faith without harassment, in accordance with the right to freedom of religion of belief."