(VOVworld) - UN Secretary-General Ban Ki-moon on Thursday urged Russia and the US to exert pressure on Syria's warring parties to cease fighting and ensure a credible investigation of the air strikes that destroyed an Aleppo hospital.

UN Secretary General Ban Ki-moon addresses a news conference in Vienna, Austria, April 26, 2016. (Photo: Reuters/Heinz-Peter Bader)

In a statement, Ban called on all Syrian parties to immediately renew their focus on the ceasefire which took effect in February.

Ban said the Geneva statement reached in 2012, and UN Security Council resolution 2254, are the only documents that can lead to a solution to the Syrian conflict.