LONDON, Feb 10 (Reuters) - Platinum, palladium and rhodium used by the auto industry to filter emissions from engine exhausts were all in short supply last year, data from specialist materials firm Johnson Matthey showed on Wednesday, as prices for the metals soared. Supply shortfalls have driven rapid price gains, with platinum trading at six-year highs and rhodium RHOD-LON and palladium close to record levels. A shortfall is expected for palladium and rhodium this year as well, the third consecutive annual deficit for rhodium and the tenth for palladium, Johnson Matthey researcher Rupen Raithatha said. Platinum may see a third consecutive annual deficit in 2021, depending on how much metal is stockpiled by investors, he said. All three metals are used in catalytic converters to reduce harmful emissions, and tightening environmental regulation is forcing auto makers to put more into each vehicle. Platinum is also in demand by other industies, for jewellery and as an investment. READ MORE