The UN's World Food Programme (WFP) on Tuesday said it had sent food aid to some 1.5 million people inside Syria in September, up from 850,000 a month earlier.

"The situation is worsening," Daly Belgasmi, WFP director for the region, told reporters in Geneva.

Last December, the UN agency had initially aimed to provide food aid to 50,000 Syrians inside the country, but that target has progressively been scaled up to reach 850,000 in August and 1.5 million in September as the crisis pitting President Bashar al-Assad's regime against rebel fighters has deepened, he said.

The situation "is becoming more and more challenging. People are internally displaced once, twice, three or four times, moving from one neighbourhood to another looking for refuge," he explained, adding: "And I'm afraid that the winter will not be helpful."

According to the UN, some 1.2 million Syrians are internally displaced, while Syrian authorities put the number at 3.2 million, Belgasmi said.

Belgasmi, who had just returned from a visit to Syria and neighbouring countries hosting a growing flood of refugees from the war-torn country, said a proposal for a four-day ceasefire starting Friday could simplify his agency's mission.

"I really hope that the ceasefire takes place," he said, pointing out that a halt in fighting "will allow us to position more food in the area, and will allow us to better coordinate."

The UN-Arab League envoy for Syria, Lakhdar Brahimi, appealed to Assad at the weekend to observe a ceasefire during a Muslim holiday starting on Friday, but fighting has so far shown no sign of easing.

Although access in many parts of Syria is "volatile", Belgasmi said, he told reporters the WFP was managing to get food aid to most places through its partnership with the Syrian Arab Red Crescent.

However, he stressed, the WFP was "dispatching" food rather than "distributing" it -- the latter implying that all the food reached its intended destination.

The WFP had also managed to deliver food aid to around 120,000 Syrian refugees in neighbouring countries, and was aiming to help nearly 500,000 refugees by June next year, mainly through a food voucher system, Belgasmi said.