Procter & Gamble (P&G), the giant consumer goods firm, has taken a stake in Ocado, the tiny, online groceries delivery business founded by three former Goldman Sachs bankers.

The owner of brands ranging from Ariel to Head & Shoulders, has spent just £5 million taking a 1% stake in Ocado as part of a larger fundraiser which realised £18 million.

It is said to be the first time that P&G, which is based in the United States, has invested in a retail business, and analysts believe it is a significant vote of confidence in the UK delivery service.

Ocado has been reported to be under severe pressure from its much larger competitor Tesco, which dominates the grocery home delivery market.

There was also concern earlier this month when John Lewis, the partnership that owns Waitrose supermarkets, moved its 29% stake in Ocado into its pension fund.

John Lewis said this "simplified and clarified" its relationship with Ocado, where there had been speculation of a rift between the two.

At the same time it signed a five-year contract with the deliverer. However, it also made it clear the two would compete within London, where Waitrose runs its own home delivery business.

The John Lewis transfer put a value of £440 million on Ocado but the P&G stake pushes it back up to £500 million. Plans for a flotation of the business, valuing it at far more than that, have almost certainly been put on hold given the turmoil in financial markets.

The biggest part of the latest fund-raising was taken by TetraPak billionaire John Rausing's Apple Trust. Already an existing shareholder in the business, it lifted its stake to around 12.5% by buying another £13 million of new shares.

P&G said Ocado could prove "a very fertile testing ground". The consumer goods giant, which also makes Fairy Liquid and Oil of Olay, has been a major user of the internet to launch and promote new products.

It said: "We think Ocado is a huge research opportunity. They have a unique business and we can learn from it. We have not exactly worked out the research projects we will be looking at, but it will give us a better understanding of how people use the internet."

This was Ocado's sixth fundraising. So far in its nine-year history it has raised a total of £295 million and has yet to make a profit.

The three founders, Tim Steiner, Jason Gissing and Jonathan Faiman, now own just over 20% of the shares between them which are valued at around £100 million.