Britain's FTSE 100 rose on Wednesday as Lloyds and Glencore gained after promising to return cash to shareholders, but Sainsbury's slumped after regulators objected to its takeover of Walmart's Asda.

The FTSE 100 was up 0.3 percent and the FTSE 250  up 0.1 percent by 0844 GMT. A decline by shopping centre owner Intu limited gains on the mid-cap index.

Sainsbury's fell nearly 13 percent after Britain's competition regulator said its deal with Walmart-owned Asda  should either be blocked entirely or require the sale of a significant number of stores and possibly one of the brands.

The stock was on track for its worst day since October 2008. Shares of Morrisons and Tesco tumbled as well.

"The  implication  of  these  proposals  are that an exit  of Walmart from the UK grocery market now seems less likely," Jefferies analysts said.

Intu Properties dropped 10 percent after it scrapped its dividend, under pressure from several retail bankruptcies. Shares of rival Hammerson fell 3 percent.

Glencore rose 3 percent after announcing a $2 billion share buyback and an 8 percent rise in full-year adjusted core earnings.

Lloyds Banking Group shares was among those gaining the most. Britain's biggest mortgage lender raised its dividend and announced a share buyback, despite weaker-than-expected annual profit growth.

Mining companies and financial services  boosted the main index. Investors were also betting on a breakthrough in the Sino-U.S. trade talks, as U.S. President Donald Trump said he was open to extending their March 1 deadline.