GENEVA (Reuters) - Syria’s government is refusing U.N. demands to deliver aid to hundreds of thousands of people including many in Aleppo, the city at the center of an eruption of fighting in the past two weeks, U.N. humanitarian adviser Jan Egeland said on Wednesday.

Journalists and civilians stand near the damage after rockets fired by insurgents hit the al-Dabit maternity clinic in government-held parts of Aleppo city, Syria, in this handout picture provided by SANA on May 3, 2016. SANA/Handout via REUTERS

“We seem to be having new possible besieged areas on our watch, we are having hundreds of relief workers unable to move in Aleppo,” he told reporters after chairing a weekly meeting of nations supporting the Syria peace process.

“It is a disgrace to see that while the population of Aleppo is bleeding, their options to flee have never been more difficult than now.”

A partial ceasefire, sponsored by the United States and Russia, was struck in February but has virtually collapsed in recent weeks, with Aleppo bearing the brunt of the renewed bloodshed.

The humanitarian task force chaired by Egeland enjoyed some success in opening up access for aid in April, ensuring it reached 40 percent of people in besieged areas in Syria, compared to 5 percent in the whole of 2015.

It has also overseen 22 airdrops of aid into the eastern city of Deir al-Zor, where 110,000 people are besieged by Islamic State insurgents, Egeland said, about half the previous estimate of 200,000 people trapped there.

But progress has stalled and requests to the Syrian government to approve aid convoys to six remaining besieged areas in May have largely fallen on deaf ears.

President Bashar al-Assad’s government refused to allow aid for about half of the 905,000 people in besieged and hard-to-reach areas, including rebel-held eastern Aleppo, and put major conditions on aid for half the rest, Egeland said.

Tawfik Chamaa, head of UOSSM, a federation of relief agencies with 850 medical workers in Syria, called on Syria’s ally Russia to prevent rebel-held areas of Aleppo coming under siege like the Yugoslav enclave of Srebrenica in the 1990s or Stalingrad in the Second World War.

“The last route to access Aleppo, called the Castello road, is threatened every day with shelling and snipers. If this road is closed it means a complete closure of access for all humanitarian needs,” Chamaa told a news briefing in Geneva.

Egeland said one town that got a partial aid approval was Daraya, where 4,000 people including 500 children are on “the brink of starvation”. The government said baby milk and school supplies could go in, Egeland said.

“But to some extent it’s an improvement - the government earlier said there were only terrorists in Daraya and they are now admitting there are children there.”

The United Nations has appealed to Assad’s government to change its mind and allow aid without conditions to all places that were refused or got only a partial green light, he said.