In the increasingly acrimonious tussle, the Takeover Panel is this weekend investigating allegations that Rentokil spread false rumours about pressure on BET from leading institutions, including M&G and Legal & General, to negotiate an agreed deal.
Rentokil chief executive Clive Thompson says no firm decision on lifting the bid has yet been made: "We have until Friday. We'll be considering the matter this week. It's much too early to comment," he said.
Analysts, however, are looking for a token sweetener of 5p-15p per BET share to seal victory.
Rentokil shares ended strongly at 368 1/2p last week, valuing its cash and shares offer at 206p per share, against BET's 207p closing price.
BET's advisers ING Barings complained to the Takeover Panel last Wednesday over misleading suggestions that the group was coming under pressure from its own shareholders.
Rentokil denies dirty tricks, but the Panel has passed on its concerns to Rentokil's merchant bankers, Lazard's.
"It is an attempt to create a false impression of what institutions believe," one BET adviser said. "The true value of BET is only just becoming apparent. Shareholders will demand a fair value from Rentokil."
In its final defence last week, BET revised forecast profits for the current year up to pounds 146m from pounds 142m and predicted a 20 per cent rise in next year's dividend.
Despite the spat, Rentokil's unbroken 14-year history of growth is expected to tell in the end.