The mayor of Tower Hamlets in east London has been accused of doubling the grants awarded to Bengali-run charities in return for electoral support.
In a BBC Panorama documentary to be shown tonight, Lutfur Rahman is accused by opposition councillors of awarding £3.6m to Bengali and Somali groups, despite recommendations by council officers that they should receive £1.5m.
Rahman, who denies the accusation, has executive power over the allocation of some grants made by the local authority.
Labour councillor Joshua Peck told the BBC: "I am pretty sure there is some quid pro quo in some of those grants decisions being made. Part of that is about supporting the mayor politically on the ground in the run-up to the election. He doesn't have a political machine and he needs organisations… making sure the electorate turns out to vote for him."
Rahman was elected as an independent mayor of Tower Hamlets in 2010. Almost two-thirds of those who turned out to vote that day were from the Bangladeshi community, according to Panorama.
Rahman said in a statement: "Panorama has been active in Tower Hamlets for nearly eight months and has only recently contacted us. Councils are complex organisations and we found that the production team had made many incorrect assumptions. It is our belief that the Panorama team formed a view and then sought the evidence to fit their story.
"Governance in Tower Hamlets is strong and the residents of the borough are proud to live in a diverse and accepting community. The picture painted by John Ware [the Panorama journalist] is not reflected in any audit or inspection reports and he makes no mention of the many excellent services provided by the council, from education to housing to street cleaning."