One secret of Trump's low-cost campaign - free labour

Campaign manager Kellyanne Conway and Paul Manafort of Republican presidential nominee Donald Trump's staff speak during a round table discussion on security at Trump Tower in the Manhattan borough of New York, U.S., August 17, 2016. Picture taken August 17, 2016. REUTERS/Carlo Allegri

NEW YORK (Reuters) - Republican presidential nominee Donald Trump has run an unusually cheap campaign in part by not paying at least 10 top staffers, consultants and advisers, some of whom are no longer with the campaign, according to a review of federal campaign finance filings.

Those who have so far not been paid, the filings show, include recently departed campaign manager Paul Manafort, California state director Tim Clark, communications director Michael Caputo and a pair of senior aides who left the campaign in June to immediately go to work for a Trump Super PAC.