The main index inched 0.2 percent higher, also boosted by oil stocks after data showed a surprise draw in US crude inventories.

The FTSE 250 was up 0.3 percent, helped by gains in industrial and oil stocks.

World markets saw an uptick after the US said it had received an indication that Beijing wanted to make a trade deal.

Washington earlier announced it would raise tariffs on $200 billion worth of Chinese imports.

Investors had remained wary all session as trade concerns dominated. Reuters sources said a draft agreement was riddled with reversals by China that undermined core US demands, backing claims that China had backtracked on almost all aspects of the deal.

China's commerce ministry said late on Wednesday it would retaliate if the tariff hikes went ahead.

"Stock markets are again tied to headlines... just like the dark days of earlier in the trade war, on the watch for signs that worst-case scenarios can be avoided," Cityindex analyst Ken Odeluga said.

Wednesday's earnings updates kept any optimism in check.

Imperial Brands affirmed its full-year forecast but the tobacco company's shares fell 6.3 percent to a more than five-year low on weaker-than-expected sales of e-cigarettes.

"Imperial's valuation is one that continues to reflect little market conviction in hitting its target," Jefferies analysts said.

Broadcaster ITV fell 6.1 percent to its worst day in more than a year as it said the late timing of Easter and political and economic uncertainty led to weaker advertising demand in the first quarter.

EasyJet gave up 3 percent while mid-cap peer Wizz Air fell 2.6 percent after Davy Research said low-cost carriers would be cautious on their second-half outlooks due to uncertainty over Brexit, higher fuel prices and MAX issues for those using Boeing's fleet.

Travis Perkins, Britain's largest distributor of building materials, gained 3.3 percent on the mid-cap index on higher quarterly underlying sales.

Pub group Wetherspoon tumbled 4.4 percent on its worst day in six months after its trading update triggered concerns over mounting costs and margin pressure.