Unit at Philadelphia refinery completely destroyed in fire - sources

June 23 (Reuters) - The alkylation unit at Philadelphia Energy Solutions Inc's oil refinery was destroyed in a fire that ripped through the East Coast's largest refinery last week, damage that will hamper the normal production of fuel, people familiar with the matter said on Sunday.

The refinery could remain shut for an extended period, Reuters reported on Friday. The blaze was still burning, according to the latest update from the company on Saturday.

Philadelphia Energy Solutions did not immediately respond to a request for comment.

Philadelphia Deputy Fire Commissioner Craig Murphy said in a press conference on Friday that the cause was unclear. (Reporting by Jarrett Renshaw Editing by Phil Berlowitz)