Syrian refugees
Syrian refugeesReuters

Syrians could soon overtake Afghans as the world's biggest refugee population, a top UN official said Tuesday, according to The Associated Press (AP).

According to the report, the number of Syrian refugees is expected to pass 4 million by year's end.

High Commissioner for Refugees Antonio Guterres spoke as the international community sharply urged Syria to comply with a new Security Council resolution demanding that President Bashar Al-Assad and the opposition provide immediate access for humanitarian aid.

Opposition activists say more than 140,000 people have died in the conflict, which enters its fourth year next month. The UN says 9.3 million Syrians are in need of humanitarian assistance.

The number of Afghan refugees was 2.6 million at the end of 2012, UNHCR says, according to AP. Syrians, with nearly 2.5 million registered as refugees, should overtake that long before the end of the year. About one-half of the refugees are children.

"It breaks my heart to see this nation that for decades welcomed refugees from other countries ripped apart and forced into exile itself," Guterres told the UN General Assembly.

Just five years ago, Syria hosted the world's second-largest number of refugees, he added.

The number of Syrian refugees now registered in far smaller Lebanon, for example, is the equivalent of having 71 million of them registered in the United States or almost 15 million in France, Guterres said, according to AP.

UN Secretary-General Ban Ki-moon said the Syrian government should allow more humanitarian workers into the country, which UN officials have called a major issue in reaching an estimated 3.3 million people in isolated areas.

Estimates provided by the UN last year said that some four million people were displaced inside Syria, in addition to the refugees that had managed to flee the country.

Refugees from Syria are a problem not only for Lebanon, but also for Turkey and Jordan, which has been forced to deal with a flood of refugees.

U.S. President Barack Obama recently promised to provide Jordan with more aid that will allow it to deal with the Syrian refugee problem.