A pub has been shut down after police spotted teenagers bragging about drinking in the bar on an Internet site.

Police launched an investigation into the Black Bull, in Kidlington, after being handed photographs showing youngsters posing with bottles of alcopops on social networking site Bebo.

The teenagers posted messages on the site celebrating how they could get away with drinking in the pub – even though they were underage.

Police said late-night lock-ins and a series of violent attacks – which included a man assaulted with a baseball bat – had also led to the closure.

Tony Cope, Thames Valley Police licensing officer, said: “The photos showed youngsters with drinks posing for photos. The intelligence we got was this was an underage drinking club and we immediately recognised it was the Black Bull.

“There were also comments bragging about what they were getting up to. Although some were over 18, many were as young as 16.

“The Black Bull was already premises we were aware of but this helped with our investigations.”

The pub was told to appear at a licensing hearing at Cherwell District Council in November after police built up a log of violence and after-hours drinking.

Licensing officers said police discovered four men drinking behind the bar at 2am last May.

Days later a man was attacked with a baseball bat, but police were not alerted.

Other evidence included a man found with head injuries at 4am on July 13 and late-night drinking involving 20 rowdy revellers on July 20.

In September, police seized CCTV footage showing curtains closed and drinks being served at 1.10am.

The council’s licensing committee ordered the pub to close, but owners Punch Taverns appealed.

The Black Bull remained open until Punch Taverns abandoned its appeal on Thursday and the pub closed its doors the following day.

Punch Taverns said it would reopen on February 28 and the firm has been ordered to find a new landlord and improve CCTV and door security.

Photos and comments by teenagers on the Bebo website have now been removed.

John Wise, Cherwell district councillor for Kidlington, said: “I’ve frequented the Black Bull in the past and stopped. I became disenchanted because no one seemed to be in charge. People seemed to be able to do whatever they wanted.

“It really needed to be done to send a message to other publicans in the area to run their premises in the correct manner.”

A spokesman for Punch Taverns said: “Our priority is to ensure our pubs provide a safe and controlled environment for responsible adults to enjoy good drink, food and entertainment.

“The Black Bull has closed for 30 days and will reopen at the end of February.

“We have already recruited a local entrepreneur, who runs another local Punch pub. We look forward to working closely with them.”

The Black Bull is the first pub in Oxfordshire to be closed following changes in the Licensing Act four years ago.