A teenager from Lewisham has been arrested after a police dog was repeatedly stabbed while chasing a suspect, leaving the canine seriously injuried.

Police dog Finn and his handler had been responding to calls from a taxi company in Stevenage on Wednesday morning when the stabbing happened.

Police in Hertfordshire said the duo were intially called to reports of a man with a gun who was robbing a taxi driver.

When they arrived at the scene, they chased a suspect who turned on them - stabbing Finn in his head and chest and the officer in his hand.

A 16-year-old from Lewisham was arrested on suspicion of GBH, conspiracy to rob, possession of a firearm and possession of a bladed article.

The dog was taken to a vet for emergency treatment, while his handler went to hospital.

According to the Twitter page for the combined dog units for Bedfordshire, Cambridgeshire and Hertfordshire police, Finn came out of surgery after four hours.

One post read: "The operation appears to have been a success & he'll now be closely monitored."

The suspect remains in custody.