Everton have called in a leading firm of restructuring and insolvency advisers, the Guardian understands, raising further questions about the proposed takeover of the Premier League club by 777 Partners.

The move came while the club were believed to be waiting for a further £15m of loans that 777 had pledged to provide Everton with during April, according to one 777 source. When asked about that £15m in loans, a 777 spokesperson said that – after a delay – “the club has been provided with the working capital it needs as of today [Tuesday]”. He would not say how much of the £15m had been provided.

Related: The Everton crisis explained: how did it get to this point?

A £15m loan would take the amount the club have borrowed from the American firm to more than £200m during the seven months since it was announced it would acquire Everton. However, 777 appears to be experiencing further financial difficulties, with its low-cost airline Bonza entering voluntary administration in Australia on Tuesday. Meanwhile, 777 Partners is understood to have parted company with its UK PR advisers after falling behind on paying its fees.

The developments raise further questions regarding whether 777 will be able to complete its takeover of Everton – and how the club will be funded until the end of the season.

When companies fall into financial difficulties, directors are required to take professional advice and closely monitor a business’s finances to ensure it is not trading while insolvent. The Guardian understands that Teneo – a global financial advisory firm with a large insolvency division – has been approached to advise Everton and its directors. When asked on Monday about the firm advising Everton, Daniel Butters, Teneo’s chief executive of financial advisory, said: “We don’t comment on any client situations.” The phone line then went dead. Everton declined to comment.

The developments also raise questions about how long the Everton owner, Farhad Moshiri, can retain control of the club, only a month after assuring fans that 777’s takeover was entering the “home straight”.

Another set of Everton creditors – MSP and its partners, the Evertonian businessmen Andy Bell and George Downing – has loaned the club about £160m, which is secured over the new stadium development at Bramley-Moore Dock, as well as a charge over more than half of Moshiri’s 94% stake in the club, according to corporate documents filed in the Isle of Man. That consortium could use its security to take control of the club.

777 did not respond to efforts to contact the company.