The UK's music festivals, sports stadiums and entertainment venues are now "on high alert" as police seek to prevent potential terror attacks, a senior officer has warned.As The Sunday Times reported, deputy assistant commissioner Neil Basu of the Metropolitan Police briefed music industry executives and representatives from Premier League football clubs last week on the threat of attacks from groups such as ISIS."These people are perfectly happy to target civilians with the maximum terror impact. Crowded places were always a concern for us, but now they are right at the top of the agenda," Basu told those in attendance.Basu explained that music festivals such as Glastonbury are "even harder to control" for police officers because "their perimeters are much larger".According to The Telegraph , Glastonbury organisers have reassured festival-goers that all necessary measures will be taken to "protect and maximise public safety". Around 135,000 people are due to attend the event in Pilton, Somerset next month, which will feature performances from Adele and Coldplay.Following last November's co-ordinated terror attack at Paris's Bataclan theatre, Basu also warned nightclub owners to be extra-vigilant. "I'm concerned about the night-time economy," he said. "I’d want to see the owners and event managers taking the same kind of security precautions."