Ukip has accused Britain's biggest business groups of "laziness and inertia" for not including the eurosceptic party's candidate for mayor of London in a major hustings event.

Peter Whittle, the Ukip candidate to replace Boris Johnson as mayor of London, was not invited to take part in the London business mayoral hustings tonight, jointly organised by the Confederation of British Industry (CBI), Federation of Small Businesses (FSB), London Chamber of Commerce (LCC), Institute of Directors (IoD) and London First.

Conservative candidate Zac Goldsmith and Labour's Sadiq Khan are set to participate, as is the Liberal Democrat candidate Caroline Pidgeon. Dee Searle, a member of the Green Party executive, is expected to stand in for the Green Party's candidate, Sian Berry.

A spokesperson for the organisers of tonight's hustings said: "It was jointly agreed by the range of organisations who arranged the London Mayoral business hustings to invite candidates from parties that currently have seats on the London Assembly."

Ukip does not hold any seats on the London Assembly.

But a Ukip spokesperson told City A.M. that the eurosceptic party "will be represented on the London Assembly" in the future and Whittle should have been included in tonight's hustings.

"This is laziness and inertia from the bureaucratic management of these business bodies," the spokesperson said. "It's amazing to think that British and London business, that succeeds due to its ability to read the situation rapidly and act under contemporary circumstances, are so ill-served by their technocrats.

"In 2014, Ukip polled more than the Greens and Liberal Democrats combined. Across the London area in last year's General Election Ukip again came third beating the Lib Dems and Greens into 4th and 5th place.

"As a fiercely pro-business and pro-entrepreneurial party we feel it is strange that the secretariat of these organisations thinks it is okay to stop their members from hearing the views of a party that will be represented on the London Assembly."

The latest Opinium poll, out earlier this week, found Khan with a comfortable lead in the mayoral contest, with the backing of 31 per cent of London voters. Twenty-six per cent said they supported Goldsmith.

Opinium found little support for candidates from other parties. Whittle was slightly ahead of Green Party candidate Sian Berry and Liberal Democrat candidate Caroline Pidgeon, though all three had the support of about two per cent of the electorate each.