Shoppers are flocking to the post-Christmas sales including online, where heavy promotions have tempted consumers away from the high street, a survey showed Tuesday.

But numbers of shoppers visiting the sales on Boxing Day, the key post-Christmas sales day for the UK retail sector, were similar to 2009, according to the survey by market researcher Experian.

Footfall in stores for Monday was up 21.5 percent compared to the same date in 2010 but that figure was flattered by Boxing Day falling on a Sunday last year, when shops have limited opening hours.

It sounds impressive but basically it's mirroring where we were in 2009, and that post-credit crunch was not a tremendous year, Experian retail analyst Anita Manan said.

Also, sales on Boxing Day last year were affected by bad weather, which kept many people at home.

This year, mild weather compared to the previous two years had helped to buoy footfall on the traditional high street, Manan said.

Online promotions led to around 96 million visits to British retail websites Monday, up 40 percent from last year, she said.

Discounting has been at unprecedented levels as retailers target consumers who have seen their disposable incomes squeezed by rising prices, muted wages growth and government austerity measures.

Retailers from London's busy West End shopping district reported brisk trade Monday despite a strike on the London underground.

(Reporting by Rosalba O'Brien. Editing by Jane Merriman.)