The FTSE 100 index was up 0.5% and the FTSE midcap index rose 0.4% by 0707 GMT.

The U.S. Federal Reserve kept interest rates unchanged on Wednesday and signalled rate cuts could start as early as July, offering respite to investors who have been uneasy about by weak economic data and global trade tensions.

FTSE 100 component Fresnillo surged nearly 7%, its biggest one-day gain in eight months, as gold prices hit their highest in more than five years after the Fed statement pressured the dollar.

Among midcaps, Dixons Carphone plunged 23.5% after it warned of a big drop in profit for the current year while  reporting a slump in full-year profit as it struggles with a fierce mobile phone market.

Homewares retailer Dunelm climbed 4.3% after it raised its annual earnings target for the second time in just over two months, capping off a year in which it saw a surge in online orders.