Sterling stabilized after worst day since 2016, FTSE 250 up 0.33 per cent

UK shares staged a fragile comeback on Friday as gains in mining and oil stocks helped revive a market battered by Thursday's sell-off, while Brexit-sensitive banking and housebuilder stocks came under renewed pressure.

The FTSE 100 was up just 0.1 per cent at 1033 GMT after briefly falling into negative territory and FTSE 250 was 0.33 per cent higher.

Both were on track for a weekly loss, with the domestically focused midcaps hit particularly hard by the rout in the pound.

Sterling stabilised on Friday after its worst day since 2016 on Thursday but was set for a drop of 1.4 per cent on the week after the resignation of key ministers threw Prime Minister Theresa May's European divorce deal into doubt.

Speculation about a possible vote of no confidence in May continued to swirl despite the defiant tone she struck on Friday, vowing to take Britain out of the European Union.

The 48 letters from Conservative lawmakers required to trigger such a vote have been submitted, the editor of BrexitCentral said on Friday, citing a single source.

Amid the uncertainty, risk-averse investors found safety in mining and oil stocks, which accounted for most of the blue-chip market's gains and were up 1.05 per cent and 0.6 per cent respectively.

Metal prices rose amid rising hopes that Washington and Beijing will resolve their longstanding spat over trade, while crude continued to recover from eight-month lows it hit earlier in the week.

Halma gained 3 per cent as investors welcomed news it is acquiring Navtech Radar, which makes security devices for road tunnels and power stations.

While the deal is small in value at only 21 million pounds, it is expected to immediately boost earnings, Jefferies analysts said.

"We believe that Navtech ticks a range of boxes, for niche presence, high returns and regulatory-, safety- and security-based drivers of growth, based on in-house technology that is already commercialised," said Investec analysts.

The company will publish interim results on Tuesday.

As earnings season neared an end, investor focus remained on politics, with housing and banking stocks continuing to bear the brunt of investor worries about the fall-out across financial markets and the economy from the torrid Brexit negotiations.

Royal Bank of Scotland lost another 2.5 per cent after suffering its worst day since the Brexit vote on Thursday as shareholders priced in a higher risk of a general election.

The Labour party has pledged in its manifesto to break up the lender. Lloyds Bank was down another 1.9 per cent while housebuilder Persimmon was down 2.2 per cent.

AstraZeneca tumbled 1.4 per cent after its immunotherapy drug Imfinzi did not meet the main goal of improving survival rates for patients with the most advanced form of lung cancer.

Among the midcaps, Kier Group gained 3.7 per cent after pledging to meet full-year targets and Centamin was boosted by a Morgan Stanley upgrade.