The parents of four-year-old Madeleine McCann, who was abducted in Portugal four weeks ago during holiday, have indicated that they will broaden their search for their daughter into a wider campaign on the issues of child trafficking and abduction.

Kate and Gerry McCann will release 50 balloons from 50 countries this Friday to highlight the fact their daughter will have been missing for 50 days.

Germany, France, Australia, Dubai, Canada, America and El Salvador are among those places expected to take part.

Mr McCann said: "We will probably have 10 centres in the UK - like Glasgow, Liverpool, Leicester - as well as Ireland and Guernsey where we have friends, and Kate and I will do the Praia da Luz one.

"We are going to tie it in with other missing kids. We were anxious about going to their countries and asking for help finding Madeleine but they have said 'what you are doing is amazing and it is helping us'."

Meanwhile, Madeleine McCann's disappearance remains a mystery after 47 days since the she has been snatched from her hotel room in Portugal.

Mr Sousa, a spokesman for the Policia Judiciara, said evidence of her abduction may have been contaminated because more than 20 people had gone into the McCann's Mark Warner holiday apartment on the night Madeleine disappeared.

He told a Portuguese newspaper that "at the very worst they would have destroyed all the evidence."

The McCanns were said to be "dismayed" by Mr Sousa's remarks.

Parents Kate and Gerry McCann, have held onto their Catholic faith throughout their ordeal of searching for their daughter, regularly attending a local Catholic church as well as recently travelling to Rome to meet Pope Benedict XVI, who prayed for the missing British girl.