Jay Slater: British teen missing in Tenerife had cut his leg and didn't ...

A British teenager who is missing in Tenerife had "cut his leg on a cactus" and did not know where he was, a friend has told Sky News.

Lucy Law said 19-year-old Jay Slater is "not a stupid boy" and would have flagged down any passing car or spoken to passers by.

Mr Slater, from Lancashire, has been missing on the Spanish island since Monday morning.

His mother, a team of mountain rescuers, and the local civil guard are searching for him after he disappeared while holidaying with friends.

Ms Law said he rang her to say he "didn't know where he was", that he "needed a drink" and had "cut his leg on a cactus".

Despite his mobile phone battery being down to 1% he managed to send her a photo of his location.

When she told him to return to where he had walked from, he said he did not know where that was, Ms Law said.

He was without food and water, she added, and had been in a T-shirt and shorts. "It's very warm in the day and very cold at night," she told the UK Tonight programme on Sky News.

"So in the day he's going to be really warm without a drink, and then at night he's going to be very cold without any suitable clothing."

Ms Law and others have printed off posters in both Spanish and English and have plastered them "everywhere", she said.

Soon after Mr Slater went missing, an American woman offered to drive Ms Law up into the mountains.

There was "literally no sign of him anywhere", she said. "We drove around all day."

Mr Slater had posted a picture online of some mountains next to a house he had been to.

Ms Law drove around looking for a lamp and some flowers seen in that picture.

"We managed to find the house," she said. "I knocked on the door and there were two people there."

They told Ms Law that Mr Slater had gone out for a cigarette before going back in and saying he wanted to go home.

"They told me he'd spoken to the next door neighbours and they'd told him there was a bus every 10 minutes back down to Los Cristianos.

"The bus stop was right next to the house. So obviously if he'd gone to get the bus he wouldn't have got lost because it [the stop] was visible from the front door."

Read more:What we know so far about Jay Slater's disappearance

The trip back down from the mountains is an hour's drive. "Everything looks the same - it's just a road and hills," Ms Law said.

"I can't understand why he would come out of the house and then decide he was going to walk. I think he maybe set off walking with battery and had not realised how far the walk actually is."

There are "so many questions that are unanswered", Mr Slater's friend said.

'He's not a stupid boy'

"The thing I find the most weird about this is the fact that there's nobody that's seen him.

"And he's not a stupid boy - he's got some nous about him.

"I've seen so many people up here and I've asked every single one if they've seen him - this is what I find weird.

"If he'd seen somebody, or a car, he would have flagged down the car - he would have said he needed a phone to contact someone."

She added: "He would never have his family worrying like this - he would never have us worrying like this.

"If he saw someone, the first thing he would do is say 'I need to ring my mum' - I know that for a fact. He would never ever have his mum worrying like this.

"It's just awful - I've never in my life been so worried.

"I've literally not slept at all since."

The Spanish Civil Guard told UK media they are "doing everything possible" to find Mr Slater.

"A specialist mountain rescue and intervention group called the Greim have been mobilised.

"A police helicopter is also out and focusing on the area around the village of Masca.

"Other emergency services including firefighters have also been mobilised."