New York-listed paper producer International Paper is reportedly mobilising to gate-crash a £5.1bn takeover of DS Smith (SMDS) .
According to Sky News, International Paper has indicated to DS Smith that it wants to launch a formal counterbid to trump an agreed offer from DS Smith by London-listed Mondi.
It was understood that if it does proceed with a formal offer - which is expected to comprise a large stock-based component - it would set the stage for a multibillion pound transatlantic bidding war for DS Smith.
Mondi announced in February that it was an exploring an offer for its smaller competitor, and this month the two companies said they had reached agreement on a deal valuing DS Smith at an implied 373p-a-share.
Some shareholders and analysts have argued that the Mondi proposal is too cheap and leaves the door open to a rival.
City insiders told Sky on Tuesday that International Paper might already have submitted an indicative proposal to DS Smith and its advisers.
The value of any such offer from International Paper was unclear, however, with industry bankers saying only that it was likely to have been pitched at north of 400p-a-share and potentially at about 420p-a-share.
One market source said the US-listed company's interest in a counterbid indicated a desire "not to be left orphaned by market consolidation".
It was unclear which bankers were advising International Paper on its deliberations.
Goldman Sachs, JP Morgan Cazenove and Citi are advising the board of DS Smith.
DS Smith declined to comment, while International Paper did not respond to a request for comment from Sky.