Fire crews have been tackling the blaze at the 20,000-square-metre warehouse since last night. It is the only Sony DADC (Digital Audio Disc Corporation) centre in the UK.
No-one is thought to have been hurt in the fire, although UK deliveries of Sony compact discs and DVDs are likely to be affected.
"There will likely be some impact on deliveries," Sony spokesperson Yoko Yasukochi told Reuters.
"We cannot determine the cause of the fire or the extent of the damage yet because it's not possible to enter the building. No injuries have been reported from the fire."
The warehouse is also home to PIAS distribution, which handles releases from independent record labels XL Recordings, Beggars, Domino, Wall Of Sound, Warp Defected, Sunday Best and Big Brother.
PIAS said in a statement: "There was a fire last night at the SonyDADC warehouse which services the physical distribution for PIAS in the UK and Ireland. PIAS is working closely with SonyDADC who are implementing their emergency plans.
"PIAS's UK offices in London and all other areas of our business are unaffected. More information will be communicated shortly to all our labels and partners."
Rough Trade East record store's Spencer Hickman told BBC 6 Music: "For us it's devastating. It's a lot of labels that are distributed by PIAS.
"It's complete chaos, we don't know how long it's going to take them to get back on their feet. It looks like people have lost everything that was in the warehouse.
"I'm sure there are labels which aren't insured. I'm sure there will be labels that will go bust."
Alex Kapranos, whose band Franz Ferdinand are signed to Domino, wrote on Twitter: "Thoughts go out to all the labels who have lost their stock in PIAS fire."
Hotel worker Tommy Thompson witnessed the outbreak, telling the BBC that he saw approximately 20 looters leaving the building with consoles, before he was assaulted.
The riots broke out in the Tottenham district of London on Saturday.
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