Last updated on .From the section Boxing

Andy Ruiz Jr (right) beat Anthony Joshua in the seventh round at Madison Square Garden in June

Unified world heavyweight champion Andy Ruiz Jr says he wants to finish Anthony Joshua's career after confirming he will contest a rematch in Saudi Arabia.

United States-born Mexican Ruiz, 29, shocked Britain's Joshua in New York in June to win the WBA, IBF, WBO and IBO world titles.

They are set to meet again in the Middle East on 7 December.

"I took it to AJ in the Big Apple and I'm looking forward to ending his career in the desert," said Ruiz.

The fight was announced by 29-year-old Joshua's camp earlier in August, but Ruiz had not confirmed his participation.

But on Saturday he posted on social media: "I'm excited to announce my rematch with Anthony Joshua.

"In the first fight I made history and became the first ever Mexican/American heavyweight champion of the world.

"I am grateful to Saudi Arabia for inviting me."

Human rights campaigners have questioned the choice of venue, citing Saudi Arabia's human rights record.

Amnesty International has said the move provides "opportunity for the Saudi authorities to try to 'sportswash' their severely tarnished image".