A hi-tech musical instrument company backed by Sony and singer Pharrell Williams is on life support from its US lender as it attempts to secure new investment.

London start-up Roli, whose rubber keyboards are used by the Canadian singer Grimes and Stevie Wonder, has stopped paying interest on more than $20m (£15m) of loans from Silicon Valley investment company TriplePoint.

The start-up, which has raised more than $100m in debt and equity funding, took out an extra $4.1m loan from TriplePoint, seeking to tide itself over in the hope of securing extra funding.

Roli made a £23m loss in 2017, the last available figures, and has been seeking new funding in an effort to move towards profitability.

Last week, TriplePoint wrote down the value of Roli share warrants, originally valued at $644,000, to $5,000 and said it was “working through a credit situation” with the company.

Roli's loans are listed as non-accrual status in Triplepoint’s accounts, meaning it has agreed to stop making payments.

The company last secured new funding last summer when it raised £10.4m, according to filings.

Roli's synthesizers use silicone keys that can be manipulated to create new types of sounds and have been used by several high-profile musicians. Mr Williams took a role as chief creative officer in 2017 and Sony’s innovation fund has invested in the company.