Ocado has not yet garnered full support for its stock market flotation, as it approaches Tuesday's deadline to price shares through an IPO.

The online grocer is understood to have orders for around 80 per cent of the shares on offer, which are expected to be priced at the lower end of the 200p-275p range, valuing the company at £800m.

Ocado, which sells Waitrose products online, is looking to raise £200m of new equity, with existing investors selling equity worth another £200m.

The retailer had hoped to get a market capitalisation of more than £1bn, but City analysts have repeatedly questioned this. Critics have argued that although the 10 year old company has enjoyed strong sales, it has yet to make a pre-tax profit, and said that it is highly over-valued.

Ocado plans to use the proceeds from the flotation, which is managed by JP Morgan, UBS and Goldman Sachs, to slash its debt and build a new warehouse.