They rose as much as 2.9 percent in midday trade and closed up 1.3 percent, outperforming their UK peers. The FTSE 100 <.FTSE> ended the day up 1.3 percent.

Market talk about the rumour was mentioned on the Financial Times' Alphaville markets chatroom.

The chatroom moderator said: "There's a mad story going round the traps about Amazon going for Morrison ... Looks to me like wild speculation, but stranger things I guess..."

The supermarket chain has struck wholesale supply deals with Amazon and is widely seen as a potential takeover target for the U.S. company as it moves into bricks-and-mortar retailing after its takeover of Whole Foods.

A spokesman for Morrisons said the company does not comment on speculation about transactions. An Amazon spokesman also declined to comment.

(Reporting by Helen Reid, additional reporting by Paul Sandl in LONDON and Jeffrey Dastin in SAN FRANCISCO; Editing by Josephine Mason and David Evans)

Stocks treated in this article : FTSE 100 Index, Wm Morrison Supermarkets, Amazon.com