Monsoon Accessorize is asking landlords to reduce rents on more than half its 258 leased stores in return for a £10m share of profits and an £18m interest-free loan to keep the company afloat.

The multi-millionaire owner, Peter Simon, has also promised to halve the £5m rent on the fashion business’s London head office, which he owns, to help reduce costs.

He has already loaned the business £12m and pledged to hand over an additional £18m interest-free loan if the rescue plan is approved.

Monsoon said it was asking for rent cuts of between 25% and 65% at 135 stores because current costs were “unaffordable, given the fundamental changes that have taken place in the retail sector”. It said a significant number of stores were unprofitable as a result and it needed to reduce costs in order to ensure their “ongoing viability”.

The plan involves two insolvency procedures known as company voluntary arrangements, which must win the backing of at least half of the retailer’s independent creditors at a vote on 3 July.

Paul Allen, the chief executive of Monsoon Accessorize, said: “Trading for the group has been difficult for some time, as it has been for much of the retail industry. This is due to a combination of factors, including rising costs, increased competition and subdued consumer spending.”

A CVA document seen by the Guardian says the company expects to fall to a £3m underlying loss this year from a £2.7m profit in 2018 as sales fall just over 3% to £358m.

“If the proposal is not approved it is likely that the company will no longer be able to trade as a going concern, which could be likely to result in the appointment of administrators or liquidators to the Company,” the document says.

No store closures are planned under the proposals but the CVA document indicates Monsoon is seeking the right to exit at least seven stores within eight months. It is not seeking rent cuts on at least seven more as these leases can already be let go at short notice.

The CVA is likely to prove controversial as Simon, who has a family fortune of £387m, according to the latest Sunday Times Rich List, has taken millions out of the company over the years.

As well as collecting £4.99m in rent on the group’s main head office in 2017, Simon’s Adena Property Investments also took £124,000 in annual rent from Monsoon on another west London office. Simon’s company Balmain Invest & Trade also received £556,000 in consultancy fees that year.

Monsoon Accesorize’s holding company also paid his family £116m in dividends between 2008 and 2013, although no dividends have been paid since then.