Black brick kilns with slave-like laborers have resurfaced in China, as 34 migrant workers were set free by a police raid in Hebei province, local media reported on Sunday.

A total of 11 suspects including the kiln's owner and foremen are under criminal detention, local police told the Hebei-based Yanzhao Metropolis Daily. The investigation is ongoing.

The men running the brick kiln, located in a remote village near the Hengshui city of Hebei, duped 35 migrant workers into working at the kiln, police said.

They forced the workers to do heavy labor 14 to 18 hours a day using beatings, electric shocks, threats and confinement, police said.

A migrant worker surnamed Song had to work 18 hours every day, and was beaten and shocked with electricity when he refused to work, the report quoted police as saying.

Song escaped from the kiln on May 18 and called the police. He said he had been taken to the kiln without any knowledge of the work conditions there. The foreman beat Song with a club after he discovered and foiled Song's first escape attempt, the report said.

Song also complained that he had not received any pay at the kiln.

Police conducted a raid on the kiln on May 21 and set free the 34 other workers, none of whom came from the area. A device used for electric shocks was found at the kiln.

The brick kiln's owner, a man surnamed Li from the local village, and the foreman surnamed Cao, were detained along with the other people running the kiln, according to the police.

Of the rescued workers, 25 have returned to their homes with police's help, the report said. The local civil affairs authority is looking after the other nine workers because they cannot get in touch with their families at present.

The case in Hebei revived the public's memories of the notorious "black brick kilns" that caused outcry nationwide three years earlier.

In 2007, brick kilns in Shanxi and Henan provinces were found to be illegally confining teenage workers and forcing them into heavy labor. Some workers were seriously injured by foremen's beatings at these workplaces dubbed "black brick kilns" by Chinese media.

The central government then launched a national campaign to crack down on illegal kilns, mines and workshops. Within two months, some 1,340 people were rescued, 367 of whom were mentally handicapped.