Family members say Laura Macintyre and Eilidh MacLeod haven't been heard from since the explosion.
Young Cancer Deaths 'Down 60%'
The number of children and young people dying from cancer in Scotland has dropped by almost 60% in the past four decades, according to new research.
Cancer Research UK said progress in treating the disease has led to this "unprecedented'' drop.
Deaths among under-24s have fallen from around 130 each year in the mid-1970s to around 45 today.
The steepest decline was in leukaemia where the average number of deaths dropped by 43% in the past 10 years, falling from 18 deaths each year to 10.
The charity released the figures as it launched Cancer Research UK Kids & Teens, a new fundraising campaign which aims to accelerate research into kinder treatments and cures for children, teenagers and young adults with cancer.
Lisa Adams, Cancer Research UK spokeswoman for Scotland, said: "It's hugely encouraging to see the death toll for children's cancers falling steadily, but we must make faster progress to save more lives.
"Cancer has a devastating impact on youngsters. Children and young people can face months of painful treatment, as well as the upset of being away from home and friends. Also, some unfortunately face living with long term side effects from their treatment, such as infertility and disability, which have an impact throughout their adult lives.
"Sadly, not every youngster survives but we continue to fight for every child and every family and hope to double the amount we spend on children's and young people's cancers in the next five-10 years.
"By boosting funding now, the best research teams could offer new hope by developing kinder and better treatments and cures, so we're urging people across Scotland to back Cancer Research UK Kids & Teens.''
The charity said it is the largest funder of research into children's cancers in the UK and urged people to donate to the campaign.
Every year, around 1,600 children aged 14 and under are diagnosed with cancer in the UK - around 110 of them in Scotland.
A further 2,200 15 to 24-year-olds are also diagnosed with the disease in the UK annually.
Three-quarters of under-15s with the disease in Great Britain are now cured compared to only a quarter in the late 1960s, the charity said.
However, survival is significantly lower in teenagers and young adults than in children for several cancer types.
The Prime Minister's wife Samantha Cameron is helping to raise awareness of the campaign and held a special reception at 10 Downing Street on Tuesday to recognise the bravery of 20 youngsters from across the UK who have been diagnosed with cancer.
A number of celebrities were there, including Peter Andre and his fiancee Emily MacDonagh, and presenters Kirstie Allsopp, Charlotte Hawkins, Sara Cox and Donna Air.
Allsopp said: "Having my children has been the biggest blessing and I cherish the time we have together. And sadly, I know all too well the devastating effect that cancer can have on families. That's why I'm supporting the launch of Cancer Research UK Kids & Teens.
"I can't imagine what it must be like to receive the devastating news that your child has cancer. No parent should have to hear that and no child should have to face it. All the money raised through this important campaign will fund ground-breaking research to beat children's and teens' cancer.''
The families of two girls from the Western Isles missing after attending the concert in Manchester targeted in a terror attack have issued appeals on social media.
Crews were called to the former Royal Victoria Hospital site this afternoon.
John Bermingham was also accused of assault and a breach of a Sexual Offences Prevention Order.
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