Charity executives have expressed serious concerns over the actions of promotions companies which organise events aimed at young Jewish party-goers.
Club nights run by commercial enterprises, which donate a percentage of their proceeds to charity, are now regular fixtures on the Jewish social scene.
But the JC has been told of concerns that the charities are receiving smaller shares of the profits than expected, and anxiety that potential donors are being drawn away from traditional fundraising ventures.
One charity director has accused the companies of "cashing in", and another now refuses to work with one company again, following claims that the charity was misled over the donation it would receive from a club night earlier this year.
The claims focus mainly on two companies, Nana Life Events and Lyla Parties, which previously operated as one company, Nana Events. Both are hugely popular with young Jews and combined have more than 1,200 followers on Facebook.
Young Meir Panim, which raises funds to relieve poverty in Israel, will not work with Nana Life Events again after a bitter disagreement over a Valentine's Day event in London's West End in February.
Tickets for entry cost £15 and flyers stated "a contribution from all tickets goes to Young Meir Panim".The charity believed it had arranged to receive 50 per cent of all ticket sales, but claims to have received only £7 for each person who mentioned the charity's name when buying tickets on the door.
A number of party-goers are known to have been given free entry by promotions staff. It is believed Nana Life Events later told the charity only around 60 people had attended, despite claiming in media reviews that more than 150 revellers were there.
A source at Young Meir Panim said: "They promised us a lot more than what we got. They promised us the world, but we had no contract with them and they changed what they said afterwards.
"We have learnt our lesson and have to warn the community and other charities."
Danny Macabi, who runs Nana Life Events, said the charity's problems had been due to a second events company, Electric Parties, which had also helped plan the evening. He voluntarily made a donation to the charity following the disagreement. Following JC enquiries, he then made a further payment last week.
Lyla Parties boasts that it regularly attracts more than 500 revellers to its events, a number which can represent ticket receipts of up to £12,000.
Last December, under the Nana Events name, a Chanucah champagne cocktail night took place at Kensington Roof Gardens. The party, in aid of Norwood, was attended by 500 people. The charity received a £2,500 donation.
Adele Breslauer, Norwood's head of fundraising, said Norwood had known in advance it would receive 25 per cent of the ticket revenue.
But she also revealed that the charity's Young Norwood group typically raises in excess of £20,000 at its own, solely organised, events.
Last August, Nana Events hosted "Encore Mania", a club night in aid of World Jewish Relief. It took place at a Covent Garden club and sold around 500 tickets, bringing in £10,000 in ticket sales alone.
WJR later received £1,500. It will also not work with either promotions company again.
The Zionist Federation does not work with outside companies. Alan Aziz, its executive director, said: "I have a problem when the punters are fooled into going to an event. When these people offer to run an event, the charities think 'ok, these people will do all the work'. They end up receiving less than they expected."
Joseph Menachem, who formerly ran Nana Events and is now a partner in Lyla, defended the companies' roles.
He said: "We do not call them charity events. We give a charitable donation and we donate a percentage of the ticket sales."