Britain's Kate Middleton has sparked rumours she could be pregnant by deciding against eating some peanut paste.

The Duchess of Cambridge turned down an invitation to taste the foodstuff - which is being sent to malnourished East African children - during a visit to a Unicef famine relief depot in Copenhagen, Denmark, with her husband Prince William, who tried some of the paste.

And speculation increased further when the 29-year-old royal was spotted rubbing her stomach at the distribution centre.

An onlooker told the Daily Mail newspaper: "It was very odd. Kate would not stop touching her tummy - it was very noticeable. She continually patted it and held her hands against it.

"She must have been doing it without realising, and at one point she had both her hands cradling her stomach."

William has previously made no secret of the fact he would like to start a family with Kate.

Speaking in November last year, he said: "I think we'll take it one step in the time. We'll sort of get over the marriage thing first, then look at the kids. But obviously, we want a family."