Denmark's Group 4 Falck, the world's second-biggest security company, is poised to make a bid for Securicor, creating a group with a market capitalisation of more than £1.6bn.
An announcement of merger talks may be made today after several weeks of talks between the companies.
Nick Buckles, Securicor's chief executive, has long said that he is looking for a "transforming deal" for the company, which transports cash and valuables, provides guards, runs prisons and provides electronic tagging services. Having lost out on potential acquisitions, such as Chubb, which was bought by United Technologies of the US last year, Mr Buckles now seems prepared to achieve greater scale by seeing Securicor taken over.
It is thought that Mr Buckles would have a seat on the board of the enlarged group. Securicor's non-executives - including its chairman Lord Sharman - are said to have been kept informed about the bid approach.
The combined sales of the companies would be £4.4bn, while it would employ 330,000 people in more than 85 countries - although it would still be smaller than the world leader Securitas of Sweden.
Mr Buckles said last year: "We want to be in the top three and to achieve that will require a transforming deal with one of the other companies in the sector."
Both companies have attracted controversy over the years, operating in the sensitive area of security, often providing services formerly supplied by the state, such as the escort of prisoners and running jails. Securicor, most famous for cash-handling, had provided the security for two of the US airports used by the 11 September hijackers.
Last week Securicor served notice that it will end its contract to protect animal testing business Huntingdon Life Sciences after Securicor's offices and management became targets for animal rights activists.
Securicor was worth £595m at Friday's closing share price of 112p, while Group 4 was valued at £1.1bn. It had been thought that any predator eyeing Securicor would wait until it became clearer how much exposure it faced from 11 September-related lawsuits.Reuse content