Western powers called for an emergency meeting of the Security Council

UN Secretary General Ban Ki-moon has warned that any forces using starvation as a tactic of war in Syria would be guilty of war crimes.

'Let me be clear: the use of starvation as a weapon of war is a war crime,' Ban told reporters.

Syrian authorities have repeatedly denied that starvation is taking place in Madaya and other towns despite growing evidence that residents have been prevented from reaching aid.

UN Secretary General Ban Ki-moon warned that any forces using starvation as a tactic of war in Syria would be guilty of war crimes

With mounting international pressure, France, Britain and the United States called for an emergency meeting of the Security Council to push demands for an end to sieges

Ban Ki Moon said that all sides, including the Assad regime, have carried out these 'atrocious acts prohibited under international humanitarian law.'

With mounting international pressure, France, Britain and the United States called for an emergency meeting of the Security Council to push demands for an end to sieges.

French Ambassador Francois Delattre said the meeting 'will draw the world's attention to the humanitarian tragedy that is unfolding in Madaya and in other towns in Syria.'

Fuaa and Kafraya, two government-held villages in northwest Syria, have been under siege by rebel groups for months.

The news come as about 17 trucks delivered aid to Fuaa and Kafraya's residents yesterday, including 6,000 children.

The two villages, along with Madaya and the nearby rebel-controlled town Zabadani, are part of a six-month truce deal that foresaw an end to hostilities in exchange for aid deliveries.

Images of starving adults and children has emerged on social media, believed to have been taken in Madaya

Activists in Raqqa posted an image of a starving boy from inside the ISIS held city in Syria

Lorries filled with aid wait for the seek of approval for delivering their aid to the civilians in Madaya

A toddler is held up to the camera, allegedly filmed inside the besieged town of Madaya

Residents who say they have received permission from the Syrian government to leave the besieged town

The UN said the next delivery would take place on Sunday.

More than 260,000 people have died in Syria's conflict, which began in March 2011 with anti-government protests but has evolved into a multi-sided civil war.

Humanitarian aid access is seen as a key confidence-building measure ahead of a new round of Syrian peace talks due later this month.

Russia, which is carrying out a bombing campaign against rebels to support its ally President Bashar al-Assad, said it had launched 'humanitarian operations' in Syria, claiming that inhabitants were returning to a 'peaceful life' there.

'In this context, the implementation of humanitarian operations will be a new line of work for the Russian armed forces in Syria,' said senior military official General Sergei Rudskoi.

Moscow also revealed that it had signed an agreement with Syria in August giving it the right to retain an open-ended military presence there.

A Syrian boy waits with his family, who say they have been allowed to leave under the protection of the Syrian government

An aid convoy entered a besieged Syrian town on Monday where thousands have been trapped without supplies for months

Across the western border in Lebanon, the secretary of state for international development Justine Greening visited a camp for displaced Syrians

Syrian refugees living in a temporary camp in Lebanon watch on after fleeing across the border

The U.N. children's agency has said that it has witnessed cases of severe malnutrition among children in a besieged Syrian town and the death of a teenager 'in front of our eyes.'

Hanaa Singer, UNICEF representative in Syria, said in a statement that the 16-year-old identified as Ali passed away Thursday in the town's clinic of severe malnutrition.

Trucks from the U.N. and other humanitarian organizations entered Madaya yesterday for the second time in a week after reports of starvation deaths. The town has been under siege for months by government forces.

Across the western border in Lebanon, the Secretary of State for International Development Justine Greening visited a camp for displaced Syrians.

She was given a tour and had a chance to chat to some of the camp residents, allowing her to see how the UK's response and aid is helping the refugee crisis.

Secretary of State for International Development Justine Greening (right) during a visit to a Syrian refugee camp in Lebanon