Vietnamese American comedian Thuy Nga's husband has said he will sue her for defamation, alleging lies she has told about him and their marriage have seriously damaged his livelihood.

Nguyen Van Nam, businessman husband of Nga, has sent a letter seeking clarification of allegedly slanderous and defamatory comments by Nga to various agencies, include the Ministry of Information and Communication, the HCM City Police and the HCM City People's Procuratorate.

"She said I cheated her USD350,000, but she does not have any evidence related to the money," Nam said in the letter.

 Nguyen Van Nam

He said Nga has no evidence that he used her name to borrow money from other people, and denied he was in hiding, as she alleged, but was living openly in HCM City.

Nam said Nga pursued him, and they had a daughter. But Nga secretly registered a marriage with a Vietnamese American man and let their daughter take the man's surname so they could become US citizens. Nam alleges Nga's actions severely damaged his reputation and that of his family.

He said he would seek to have Nga prosecuted if she continuous making slanderous or defamatory statements about him. Nam wants an apology and a public correction of comments made within 15 days of his letter.

Nga has made public legal advice sent to the Law Office of Nguyen Van Hau and Co., explaining her marriage to Nam. In that communication, she alleged she had sympathised with Nam's declining business and took part in a marriage ceremony with him in 2010, but the marriage was never registered with Vietnamese authorities.

 Wedding photo of Nam and Nga

"I and Nam did not live together as husband and wife because I discovered that he had been borrowing money from many people and did not repay the debt, including to me and my family," Nga wrote in the letter to her lawyer, "He told everyone that he was Thuy Nga's husband to establish reputation and borrow money. I was shocked and hurt and felt my reputation was damaged upon discovering the facts."

Nga questioned whether she and Nam could be considered legal couple and how to deal with the problem. She received a response that they are not legal husband and wife as they did not register their marriage. The response went on to say that since Nga did not sign on any loan contracts, she bore no responsibility for their repayment.

Nga alleged she discovered Nam was out to steal her assets three days before the wedding ceremony, but decided to go ahead.

"I went along with the ceremony to have proof about our relationship, but he still carried out his plan and ran away with my money," she said, adding she wants the truth about Nam known.