Dutch and Belgian supermarket giants Ahold and Delhaize have refused to comment on mounting speculation that they are in talks on a possible merger, Dutch media reported at the weekend.

Two Belgian newspapers say that talks are under way between the two companies. According to Rabobank, a merger would generate savings of €1bn a year and create one of the five biggest supermarket groups in the world.

Belgian business paper De Tijd said the two companies are in early stage talks, basing its claims on several company sources.

According to the Volkskrant, Ahold and Delhaize came close to a merger in 2006/2007 and had even agreed to base their headquarters in Brussels.

So far this time round, there is no agreement on price or structure, De Tijd said.

Dutch market leader Ahold has 30 Albert Heijn shops in Belgium, while Delhaize has a 22% market share. Both companies are also active in the US.

Shares in both companies rose sharply on Monday morning. Ahold was up 8% in early trading in Amsterdam while Delhaize rose 12%.