An unprecedented raft of “secret Sales” and promotional vouchers is likely to spark a high street bloodbath ahead of what retail chiefs are warning will be the toughest Christ-mas ever.

Yesterday Marks & Spencer launched a 20 per cent-off Sale, its first pre-Christmas Sale since 2004. It is believed that the promotion was a last-minute response to dire trading. It fell in the middle of Debenhams’ three-day spectacular, which promised£200 million of price cuts.

Marks & Spencer executive chairman Sir Stuart Rose said “the signs are not encouraging” for Christmas and retailers would be fighting for their share of the “limited pot of gold”.

Debenhams deputy chief executive Michael Sharp said retailers were “staring into the face of the worst Christmas we have ever had”. He said that while retailers do not plan to go into full Sale before Christmas “nobody knows how it will pan out”.

In recent weeks, discounts have been launched by retailers including Warehouse, Oasis, Topshop, Bhs, House of Fraser, Wallis, Gap, and Goldsmiths.

It is expected that many retailers will have gone into Sale by the last weekend before Christmas as consumer confidence continues to fall. Sales at retail bellwether John Lewis slumped a startling 14 per cent in the week to November 15.

The slashing of the interest rate by 1.5 percentage points earlier this month has done nothing so far to stimulate festive spending, according to updated GfK NOP data. The average planned spend for Christmas fell from£609 in late October to£580 by mid-November.