Madeleine McCann's parents are defending British police for spending more than €Â€13 million trying to find their daughter.

Wednesday marks ten years since the 3-year-old toddler went missing in Portugal, while on holiday from the UK.

Police forces across Europe have searched for her ever since.

Madeleine's parents say they have seen the best and worst of human nature - with online messages from both well-wishers and trolls.

But Gerry and Kate McCann say no parent could put a price on their child: