A zoo keeper went above and beyond the call of duty after licking a constipated monkey's bum for an hour.

Zhang Bangsheng stepped up for the gruesome task when the cute Francois' leaf monkey ate a peanut which was too big to pass through its digestive system.

As three-month-old animal was too small for medication, the 50-year-old keeper, who works at Wuhan Zoo in China, set to work.

He first washed the monkey's bum, then he licked it with his tongue for 60 minutes.

After an hour had passed, the monkey finally passed the peanut through its pooper.

Zhang said he "laughed with satisfaction" when the nut finally materialised.