Nobel Peace Prize winner and campaigner Malala Yousafzai has marked her 18th birthday by calling on the world’s leaders to stop "failing" the people of Syria.

Malala, who was speaking at the opening of a Malala Fund girls' school in Lebanon's Bekaa Valley, close to the Syrian border, described the situation in neighbouring Syria as a "heartbreaking tragedy".

The world renowned Pakistani teenager, who settled in Birmingham after being flown to Britain for treatment for gunshot wounds back in 2012, also announced a new grant of 250,000 US dollars (£161,000) to support Unicef and UNHCR refugee programmes in Jordan.

The co-winner of the 2014 Nobel Peace Prize said she felt honoured to spend her birthday - the third annual Malala Day - with "brave and inspiring" girls from Syria.

Speaking at the opening the girls' school, Malala said: "I am here on behalf of the 28 million children who are kept from the classroom because of armed conflict.

"Their courage and dedication to continue their schooling in difficult conditions inspires people around the world and it is our duty to stand by them.

"On this day, I have a message for the leaders of this country, this region and the world - you are failing the Syrian people, especially Syria's children.

"This is a heartbreaking tragedy - the world's worst refugee crisis in decades."

In the run-up to Malala Day, people globally have taken action in support of her fund's £BooksNotBullets campaign to highlight the importance of quality education for girls.

Malala, who was shot in the head by the Taliban in October 2012 after campaigning for girls' rights to education, added: "On behalf of the world's children, I demand of our leaders to invest in books instead of bullets.

"Books, not bullets, will pave the path toward peace and prosperity. Our voices will continue to get louder and louder until we see politicians and our governments invest in the education of their youth rather than military and war."

Additional reporting by Press Association