More than a kilometre away from the house where the child disappeared, Britons Chris Hills and Lief Stone, aged 37 and 33, respectively, are riding their bikes in an attempt to find the trail of Noah, aged two and a half.

"I saw what was happening on television and on Wednesday night I came to participate in the search," said Lief Stone, who has two children, to Lusa.

Today, together with his friend Chris Hills, the construction workers took the day off work to participate in the searches and hope for a "happy ending".

"We tried to come to the riverside from the child's parents' house," they said.

This afternoon, Captain Jorge Massano, from the Castelo Branco GNR, announced that he was going to expand the search "from the outside to the inside, using all terrain vehicles", to try to find the child.

At this afternoon's conference, the person responsible for the operation said that the "search effort" will focus on an area where a boot and children's shorts were found, which is about 1,300 metres from where a sweater of the child had already been found.

According to Jorge Massano, 127 elements continue to be involved in the operations, including GNR, firefighters, municipal civil protection and volunteers, with the support of technical teams, drones and divers, who are inspecting wells and water courses.

The toddler is said to have disappeared on Wednesday from his parents' house, located about 1.5 kilometres from the centre of Proença-a-Velha, between 5:00am and 8:00am.