Essien, who had been sending threatening letters to the singer since 2009, has been warned to stay away from the 31-year-old star, a website reports.
Knowles had also won an anti-harassment order in court in 2011, prohibiting him from troubling her.
“Staff have been briefed on the situation and pictures of him have been passed round. They’ve been told to keep their eyes open and be extra vigilant,” a source said.
“Security has been increased on a few engagements now, especially for her (British) promo. It is believed similar letters to the ones that Essien sent have been received,” he added.