The United Nations' humanitarian chief, Valerie Amos, told Syrian officials fuel shortages are slowing aid deliveries to an estimated 2.5 people in desperate need, according to BBC News.
The UN chief is visiting Damascus, where she demanded that the agency be allowed to import fuel in order to distribute supplies. The government promised to respond to her request on Tuesday, reported the Associated Press.
"If we are truly to make use of the access that the government says we can have, it means that we have to cross lines, we have to move from government-controlled areas to disputed areas to opposition-controlled areas," BBC cited Amos as saying.
She also requested access to 10 more aid agencies, said BBC, and informed the regime that the agency will be pursuing "opposition contacts," said AP.
Syria is reeling from a humanitarian crisis brought on by 21 months of brutal fighting between Syrian President Bashar al-Assad's forces and an armed insurrection against his rule.
International efforts have failed to find a solution to conflict, which has killed an estimated 40,000 people.
The UN withdrew "all non-essential international staff" from the volatile country earlier this month, said BBC.