Shares in Anglo-Dutch steelmaker Corus have jumped after the Financial Times reported that it had held merger talks with Russian rival Evraz.
A tie-up between the two could potentially create one of the world's six biggest steel firms.
Neither company was willing to comment on the speculation.
News of a prospective merger comes as the world's leading steel firm Mittal is trying to consolidate its position by taking over close rival Arcelor.
According to the report in the FT, which cited sources close to the talks, Corus and Evraz have held discussions about a possible merger for several months.
Corus has long been the subject of merger and acquisition speculation.
Last week, chief executive Phillipe Varin said the firm was hunting for potential partners around the globe who could provide it with low-cost raw steel - Evraz could fill that role.
News of the talks propelled Corus shares to levels not seen since late 2000 on the London market.
By the close its shares were up 9.5 pence, or 11.24%, at 94p.