The FTSE 100 was up 0.2% by 0704 GMT. The mid-cap FTSE 250 rose 0.3%, helped in part by a surge in rail and bus operator FirstGroup.

Oil majors Shell and BP boosted the main share index as oil prices rose on Thursday after an industry report showed a bigger-than-expected decline in U.S. crude inventories, though global trade uncertainty still loomed.

Markets have been bracing for the possibility that a resolution to the Sino-U.S. spat may not be imminent. China fired another shot at the United States on Thursday as Vice Foreign Minister Zhang Hanhui said provoking trade disputes was "naked economic terrorism".

FirstGroup, under pressure from a shareholder to make strategic changes, jumped nearly 11% to a near two-year high after it put its U.S. coach service Greyhound up for sale and also said it was looking to separate its UK First Bus operations.

Among smaller stocks, De La Rue Plc tanked 19% and was on course for its worst day since September 2014, after the banknote and passports maker warned of "somewhat lower" profit in fiscal 2020 and its chief executive would stepped down.