HONG KONG — Trinh Xuan Thanh, a high-powered construction executive in Vietnam, fled the country last year amid accusations of economic mismanagement and ended up in Germany, where he applied for asylum. Officials in Berlin were scheduled to hear his case on July 24, but he didn’t show up.

Mr. Thanh, 51, became the subject of an unusual and mysterious diplomatic spat on Wednesday, when Germany publicly accused Vietnam of abducting Mr. Thanh and forcibly returning him to Vietnam.

On Thursday, Vietnamese officials offered a vague statement of regret, and in the evening, state-run television broadcast images of a haggard-looking Mr. Thanh.

“With encouragement from my family and friends, I came back to Vietnam and turned myself in to seek the forgiveness of the party, the government and the law,” Mr. Thanh said in the broadcast, referring to the ruling Communist Party.