LONDON (Reuters) - Sales at Tesco (>> Tesco PLC) fell 1 percent year on year in the 12 weeks to May 22, according to industry data published on Wednesday, showing signs of stabilisation for Britain's biggest supermarket chain in a tough market for the "Big Four" players.

Tesco outperformed its main rivals, with sales at Sainsbury's (>> J Sainsbury plc) down 1.2 percent while Wal-Mart's (>> Wal-Mart Stores, Inc.) Asda suffered a 5.1 percent fall and Morrisons (>> WM Morrison Supermarkets PLC) dropped 2.1 percent, Kantar Worldpanel said.

All four companies are being squeezed by the march of the discounters in Britain, led by Aldi [ALDIEI.UL], which increased sales by 11.4 percent, and Lidl [LIDUK.UL], up 14.2 percent.

"The big four continue to be under pressure, with sales declining at each retailer this period," Kantar said. "Tesco saw signs of stabilising in comparison to historic declines over the past two years."

(Reporting by Paul Sandle and Costas Pitas; Editing by David Goodman)