Busaba Eathai has become the latest casual dining chain to undergo a company voluntary arrangement (CVA), with one restaurant likely to permanently close.
Nine of the Thai restaurant group's 13 London sites are currently trading, though the intention is to eventually reopen 12.
Busaba's three restaurants in Leicester Square, the O2 Arena and Covent Garden are temporarily shut.
Terry Harrison, managing director of Busaba, told The Caterer its site in Eastcastle Street, Fitzrovia, is not expected to reopen.
Harrison said: "There's just no footfall, though we are in conversations with the landlord of the O2 about what reopening will look like.
"[Across the nine open restaurants] some are doing slightly better than others, but it's still pretty tough."
Busaba was acquired by London-based private equity firm Tnui Capital earlier this year. It started the CVA process in July and creditors voted on the restructuring on 28 September.
Harrison said the introduction of Tier 2 restrictions in London earlier this month had severely impacted trade.
He said: "Just before going into Tier 2 it felt like we were building towards some sort of new normality, but we've probably lost about another 20% of sales since [the restrictions came in].
"Our challenge is to keep as many people as possible in some work. We've tried to spread the hours across as many staff as we can.
"We feel like we're in limbo in Tier 2. We're getting the impact of people being nervous [to eat out] without the full support.
"We will use the Job Support Scheme as it can help us, but it's not the silver bullet. What we need is people back in restaurants – London is decimated. Busaba is a London-centric business, so it's particularly difficult for us."
Busaba was founded by Alan Yau, the restaurateur behind the Wagamama and Hakkasan groups, in 1999.
Other casual dining chains which have used CVAs to restructure since March include Wahaca,Pizza Express, Gusto and Thai Leisure Group.