Bonmarché has unanimously rejected the offer made by prospective buyer Philip Day, and said the cost-reduction plans of its board will succeed “in the medium term”.

The embattled womenswear retailer has urged shareholders to reject the £5.7m bid made by Edinburgh Woollen Mill owner Day, as the bid “materially undervalues Bonmarché and its prospects”.

The retailer said the “cost-reduction actions”, which the board began at the time of the bid, have now “begun to be implemented”. The delivery of this programme should “result in the improved operational and financial performance of the business”, it said.

It is the latest twist in the ongoing battle between Day and the Bonmarché board for control of the company.

Under Takeover Code rules, any shareholder with a stake of more than 30% is required to make a full takeover offer for the business. Day has a 52.4% stake in the business.

Day made an 11.45p per share offer for Bonmarché through his Dubai-registered company Spectre on April 2.

On April 12, however, directors warned Day his offer “materially undervalues” Bonmarché but did offer further talks.

However, it now seems the retailer has taken a firmer stance with Day and Spectre, and has asked shareholders not to “sign any document which Spectre or its advisers send to you”.

Since leading a management buyout of EWM in 2002, Day has expanded the retailer’s portfolio of high street names, acquiring Austin Reed, Jaeger, Country Casuals, Jacques Vert and Peacocks.

Peacocks owned Bonmarché until early 2012 when it sold the business to Sun European Partners in a pre-pack administration deal.