German police have launched an investigation into two teenagers accused of controlling a robot that allegedly groped a 16-year-old girl.

Police in Cologne have confiscated the red and gold robot that allegedly grabbed the girl's buttocks and made thrusting motions against her before she screamed and moved away.

North Rhine-Westphalia Police said the robot's 16-year-old owner and his companion, 19, are believed to have streamed the incident live on social media and commented on it.

According to a police statement on Facebook, the 120cm (3.9ft) tall device approached the girl from behind while she was with her friends close to midnight local time (23:00 BST) on Saturday.

The girl was in front of a fast-food outlet near the city centre when the incident took place, police said.

Emergency services were alerted, and the teenage boy and the man now under investigation with him were found a block away a short time later. The robot was discovered in the back of a car, where the boy had placed it, police said.

A photo released by police showed the robot wearing a black moustache, a gold-coloured chain and a white vest.

Along with the robot, police seized two mobile phones belonging to the suspects. They are trying to determine whether someone was deliberately controlling the robot's movements at the time of the incident.

In a follow-up post on Facebook, police warned that some social media comments on the case "can be a crossing of the line and, in the worst case, a criminal offence".