LONDON (AP) — GardaWorld, the world’s largest privately owned security company, said Monday it was making a 3 billion-pound ($3.9 billion) offer for G4S, saying its London-based rival has rejected or ignored three previous approaches.

Montreal-based GardaWorld says it decided to publicize its bid of 190 pence a share - a 30% premium to G4S’s closing price on Friday - to pressure the firm into talks.

GardaWorld says the company’s expertise will help turn around G4S, which has failed to deliver “for shareholders, customers, employees or the public.”

“G4S needs an owner, not a manager. GardaWorld has 25 years of experience in the sector and we know how to improve and repurpose this business,’’ Stephan Cretier, founder and chief executive officer of GardaWorld, said in a statement. “As owner-operators, we believe that the combined business’s operations will offer a better future for all those who depend on G4S.’’

London-based G4S employs more than 500,000 people in 85 countries. The company said it had no immediate comment on the GardaWorld offer.