Yobs are singling out foreign language students to bully and rob on Oxford's Blackbird and Greater Leys estates.

Police said there had been three incidents at Gillians Park and one in Spindleberry Nature Park in the past few days.

In the most recent incident, a group of three young white teenagers -- including one armed with a knife -- threatened a man because they mistakenly believed he was from overseas.

They swore at him, called him French, and demanded his wallet. However, when he replied they were surprised to hear he had an English accent.

The 17-year-old victim told police one of the group then "almost apologised" for singling him out. Nothing was taken. The incident happened in Gillians Park at about 9am on Monday.

Det Sgt Rebecca Mears, of Oxford police's robbery team, said: "The conversation which occurred between the victim and the offender confirmed our concerns that foreign students are being targeted."

A Chinese student was pushed to the ground and robbed of her bag by a white youth and a black youth in the park at about 6.45pm last Friday. About an hour later, two Chinese students were forced to stand up while a couple of white youths searched them. Nothing was taken.

A French student was robbed shortly after 11pm last Wednesday in Spindleberry Nature Park. A group of about eight people took his bag and threw it around, before one ran off with it. The victim tried to retrieve the bag and was pushed into a hedge.

The Oxford Mail reported last month how an Italian student carrying a bag marked with the logo of EF language school was robbed in Blackbird Leys.

Jane Collis, principal of Bellerbys, a college in Blue Boar Street which offers English tuition, said her pupils had been shocked by the behaviour of English people. She said: "It's tragic and embarrassing that our own population behave so loutishly."

Call Oxford police on 08458 505505 with information.