The Meetings Industry Association (MIA) has called for an extension of furlough for the sector after its research found that few operators were able to open before October and that job losses could pass 250,000.
Though meetings of up to 30 are currently permitted, few venues are open as a decline in consumer confidence has seen enquiries dry up.
Having compiled figures for the Department for Digital, Culture, Media & Sport, the MIA found that over a third of 197 venues were predicting losses of £1m-£5m, with the average business down £2.4m.
It predicts that it will be at least 12-18 months for the sector to recover to pre-Covid levels of business and that some 266,000 jobs will be lost as a result.
MIA chief executive Jane Longhurst said: "Despite events now being permitted for up to 30 people in Covid-secure venues, the industry is yet to see the green shoots of recovery."
She added: "To ensure the sector is able to survive and facilitate the £165b of trade that takes place through business events, we need further support."
The association is calling for an extension of the furlough scheme into 2021 to stem the predicted 266,000 job losses.
Longhurst said: ""With government intervention, including the extension of the furlough scheme and other support, 75% of venues indicate that this figure would be drastically reduced, with 140,000 jobs across the industry expected to be saved. The government therefore has a simple choice, to save jobs by offering an extension, or fund those individuals through benefits."