Wall's Solero Getfruit! consists of one-litre tubs of ice-cream and fruit puree, and is being trialled in Tesco stores.
Its label says the product 'contains at least 45% real fruit'. The pack also says: 'It is important to eat more fruit but not always that easy. Getfruit! is made with real fruit puree and contains vitamin C to help you and your family reach your target of 5-a-day. Each 125ml serving contains half a portion of fruit'.
A spokesman for WHO said: "We tend to see this as an attempt to hijack '5-a-day' and use it in ways not entirely in keeping with the spirit of the concept."
It is the second time in a month Unilever has landed in hot water over its use of '5-a-day' claims. In January, the Department of Health rejected its assertion that its Knorr Vie soups contain three portions of fruit or vegetables.