A serial killer who murdered six people and raped 10 women and two girls, including a 12-year-old, was executed on Tuesday in China.

Zhao Zhihong, 47, known as the “smiling killer”, was sentenced to death in Inner Mongolia in 2015 for crimes committed in the northern region between 1996 and 2005.

He strangled most of his victims with his hands but killed one with telephone wire and slashed another.

“The nature of his crimes was particularly gruesome,” said the Supreme People’s Court, which has the final word on executions.

Chinese journalists who met Zhao dubbed him the “smiling killer” because of his seemingly unflappable demeanour.

Zhao was arrested in 2005 and confessed to a string of crimes, including the 1996 rape and choking to death of a woman in the toilet of a textile factory in Hohhot, Inner Mongolia’s capital.