The mother of a missing 11-year-old has begged him to come home and revealed that he was not looking forward to going back to school.
Police are worried about missing Rory Blackhall
Rory Blackhall has not been seen since he was dropped off at Meldrum Primary in the Deans district of Livingston, West Lothian, at 0830 BST on Thursday.
Appealing for information to help trace him, his mother Michelle said he is an "affectionate" and "loveable" boy.
Police officers were concentrating their search at transport links.
They have been carrying out enquiries at train stations and speaking to bus and taxi drivers.
Officers on horseback and dog teams are also scouring the areas around Deans Industrial Estate and the Deans Reservoir.
Rory's family only realised something was wrong when he did not return home on Thursday afternoon.
Police said they were very concerned for his safety.
Speaking at a press conference, Mrs Blackhall, a 41-year-old primary school teacher, said her son had had a difficult year and had been unhappy about having to go back to school.
Addressing reporters, she said: "If you are watching sweetheart, come home. Mummy and daddy love you very much."
"He has nothing to worry about at all," she added.
The youngster, from the Adambrae area of Livingston, is keen on trains, dogs, diving and fishing and officers say there is a "distinct possibility" he may have tried to travel to Edinburgh by rail.
Mrs Blackhall said Rory, who has an older brother aged 14, has had a hard time recently.
She said: "There have been things happening within the family that have upset Rory - a number of things over this year.
"I think this final thing of going back to school, he was unhappy about.
"He wasn't looking forward to it. I think that kind of tipped the balance."
She described her son as "a very loveable boy who gets on with everybody" and said he was "very affectionate".
"He's just a fantastic child," she added.
Police have also been speaking to parents and pupils at Rory's school but said that "there is nothing to suggest anything untoward has happened to him".
The hunt was being led by Chief Inspector Jim Thomson, of Lothian and Borders Police.
"We are becoming increasingly concerned for Rory's welfare as he is only 11 years old and has not been seen for more than 24 hours," he said.
"His family are extremely worried about Rory and are desperate for him or anyone who might know where he is to contact them."
He added: "We carried out some searches last night and will be doing further, more detailed ones today with specialist officers.
"It is out of character for him to go missing and we would appeal to anyone who may recognise the description of Rory to contact police immediately."
Rory is 5ft 2in tall, of slim build, with a pale complexion, blue eyes and dark brown short hair.
When last seen he was wearing a navy jacket with a white stripe on the sleeve, a black Meldrum Primary School sweatshirt, a red polo shirt, grey trousers and black shoes.