Christians around the world joined in prayer on Friday for the safe return of missing Madeleine McCann and the release of all children held by criminal networks.

Madeleine was three when she was abducted from her family's holiday apartment in Praia de Lux in Portugal on 3 May 2007. Her parents, practising Catholics Gerry and Kate McCann, have since kept up a worldwide search for their daughter.

The worldwide day of prayer was organised by the Madeleine Prayer Circle.

The group's John Wearne said that the group formed when he met Nina Jones and discovered they and many other Christians share a concern for the missing girl.

He said that the group were focusing their prayers on Belgium and surrounding countries out of a belief that she may be hidden in this region, according to Assist News.

Wearne told the agency, "The McCanns are Christians and pray as we do for her safe return."

The worldwide day of prayer on Friday focused on Madeleine and many other children being held prisoner by child trafficking networks.

"We feel that the battle is spiritual and by going through prayer that God will listen to the cries of His people and that this will sway the spiritual balance in Madeleine's favour," said Wearne.

"Everything is done through God and there is total belief that one day Madeleine will one day come home. God may have a greater plan for others and may well be using Madeleine in that plan. We petition God always for His will to be done and ask that Madeleine be brought home," he said.

Wearne said as many as six million children went missing each year.

"The problem is worldwide. The problem is that due to the power involved in child trafficking the numbers are hard to ascertain, but the figure would probably be around 6 million children that go missing every year. In Spain and Portugal there are also serious concerns. The prayers are needed not just for Madeleine, but for these other innocent children," Wearne told Assist.

He added, "Prayer is the way forward for us now, rather than active involvement."