G4S said today that US-based Allied Universal Security Services has expressed interest in a potential offer for the British company.
In recent weeks, G4S has repeatedly rejected a hostile takeover attempt by Canada's GardaWorld.
G4S, one of the world's largest private security companies, reiterated that shareholders were strongly advised to reject private-equity backed GardaWorld's 190 pence per share offer valuing it at £2.97 billion.
Shares in the London-listed company jumped on the prospect of another offer on the table, rising 5%.
Its stock has gained 38% since GardaWorld first made its offer public on September 14.
The British company has a market capitalisation of £3.12 billion as of yesterday's close.
GardaWorld is majority owned by buyout firm BC Partners.
It said this week it had begun meeting with key G4S shareholders regarding its offer, which the G4S board called "unattractive and opportunistic".
