(Updates prices) Dec 14 (Reuters) - London base metals rose across the board on Monday, lifted by optimism about progress on the COVID-19 vaccine front, prospects of additional U.S. economic stimulus, and hopes for a Brexit deal after talks were extended beyond the Sunday deadline. Markets cheered news about U.S. regulators giving emergency-use authorisation for the Pfizer/BioNTech vaccine, seen as pivotal to halting the country’s resurging coronavirus cases. “More positive news flow is likely on this front with Moderna’s vaccine likely to receive emergency-use authorisation by Friday,” said Tapas Strickland, an economist at National Australia Bank. Another reason is that “the EU and the UK agreed to extend trade talks (again), averting near-term risks of a hard exit,” Strickland added. Nickel led the gains, with higher stainless steel prices and demand in China and news that a nickel smelter in New Caledonia was running low on ore giving the metal used in stainless steel and car batteries a further boost. Three-month nickel on the London Metal Exchange rose 1.9% to $17,610 a tonne by 0735 GMT, after hitting $17,780 earlier in the session, its highest since Oct. 11, 2019. The most-traded February nickel on the Shanghai Futures Exchange ended daytime trade up 1.6% at 130,930 yuan ($20,020.80) a tonne, advancing for a sixth consecutive session. * The nickel smelter of Eramet SA’s SLN subsidiary in New Caledonia is running low on ore due to widespread protests over the sale of another nickel operation in the French Pacific territory. * In London, copper rose 0.3% to $7,799.50 a tonne, aluminium gained 1.1% to $2,043.75, zinc added 0.9% to $2,821 a tonne, lead gained 0.1% to $2,063.50 a tonne, and tin climbed 0.4% to $19,500 a tonne. * In Shanghai, copper slipped 0.5%, aluminium lost 0.4%, zinc dropped 1.7%, lead slid 0.3%, and tin eased 0.2%. (Reporting by Enrico Dela Cruz in Manila; Editing by Uttaresh.V, Sherry Jacob-Phillips and Subhranshu Sahu)