Nan'an, a city under Quanzhou of Fujian province, has punished eight officials in its Xiangyang township after a man posted messages online claiming that his father and daughter had been locked in the township's family planning service institution.

Lin Tiesheng, 29, a township resident, posted a picture on his weibo account on Wednesday that showed eight people, including two children, locked behind a barred gate.

Lin said the picture was taken in the township's family planning service institution. Among those it showed, he said, were his 63-year-old father and 2-year-old daughter.

Lin said his father was taken to the family planning service institution on Tuesday because local officials wanted to collect a fine of more than 20,000 yuan ($3,200) from Lin and his wife, who had given birth to their only child before they were married.

According to Fujian province's family planning regulations, those who enage in "conception before getting married" will be fined.

Lin said he and his wife had been doing business in Wenzhou, East China's Zhejiang province, and were thus out of the reach of Nan'an authorities. As a result, his father, who had been taking care of the child by himself, was taken away instead, Lin said.

The old man had to take the 2-year-old girl with him, since "she is too young to be all by herself", Lin said.

Lin said his father and daughter were locked in the room for two nights and were released with the other captives on Thursday, after the local government had seen the online message.

The Nan'an government punished eight officials for being involved in the incident, either by firing them, demoting them or giving them warnings, China Youth Daily reported on Sunday.

Dai Weiming, an official of the township's family planning office, said that it was a janitor who had "inadvertently" locked them behind the gate.

"We have already visited each of them and apologized," Dai was quoted as saying.

He has been demoted.