The United Nation’s top aid official is making his first visit to Syria in a bid to step up relief efforts in what has become the world's worst humanitarian crisis. Nearly 12 million people have been displaced because of Syria's war that began in March 2011 and around 240,000 have died, AFP reported.

New U.N. Under-Secretary-General for Humanitarian Affairs Stephen O'Brien succeeded his predecessor Valerie Amos in May, who last visited Syria in January 2014.

The visit comes amid a newly released a video from the Islamic State group (ISIS) Friday showing two men, suspected of being gay, being thrown from a roof and then stoned to death.

Intense fighting across the country has caused a surge in displacement, O'Brien told the U.N. Security Council in July, noting that more than 100,000 people fled the southern areas of Al-Hasakeh following the Islamic State group's advances last month. Both the U.S. and Russia have called for renewed peace talks to end the war.

O'Brien began his trip Friday in Lebanon where he met with Prime Minister Tamam Salam, followed by a meeting with Syria's Deputy Foreign Minister Faisal Mekdad on Saturday, AFP reported.

The U.N.’s chief aid official posted on Twitter that he traveled to the central Syrian city of Homs, where the two men were thrown from the roof Friday, meeting with some of the first displaced people to return to Homs.

O'Brien also held talks with local governor Talal Barazi on Saturday. "Visited Homs today. Beyond destruction of buildings lies destruction of lives. Syria needs peace," O'Brien wrote on his Twitter account after the visit.

“We are committed to continuing to support humanitarian efforts in Syria. Equal access to all people in need vital for our work,” O'Brien Tweeted Saturday.

O'Brien is scheduled to hold a press conference Monday in Damascus, the capital of Syria. 

The top aid official told the Security Council in July a political solution was urgent as the crisis was deteriorating in Syria. Another “tragic milestone” was recorded last month, O'Brien said, when the number of registered refugees reached 4 million in early July, making it the largest refugee population from a single global conflict in more than a quarter of a century.

"There are no humanitarian solutions to this crisis," O’Brien told the Security Council at its meeting on the situation in Syria last month. "Each day that passes without the parties upholding their most basic obligations to protect civilians, and the strong demands of this Council, only results in more lives lost; more people displaced; more people without access to basic services; and a generation of children who struggle to obtain an education or have any sense of a future for themselves."