Activists say the Yarmouk district in southern Damascus is experiencing continued bombardment and fighting between armed groups, a situation a UN official has described as "beyond inhumane".

Hatem al-Dimashqi, an activist based in an area just south of the Syrian capital, said the Yarmouk camp witnessed sporadic clashes and shelling on Monday.

Both Al-Dimashqi and the London-based Syrian Observatory for Human Rights, which monitors the Syrian conflict through a network of local activists, said Syrian government's air force has dropped several barrel bombs on the camp since Sunday.

Quick Facts: Yarmouk Established in 1957 as a camp for Palestinian refugees. Turned into a residential neighbourhood housing Palestinians and Syrians. 8km from the centre of Damascus, covering 2.1 sq km. The Syrian uprising, starting in 2011, has divided Palestinian groups. Some oppose the Syrian regime while the Popular Front for the Liberation of Palestine - General Command (PFLP-GC) backs it militarily. Yarmouk became the focus of heavy fighting in late 2012 when armed groups, including the Free Syrian Army and the Nusra Front, moved in. Most residents fled as Syrian regime forces and the PFLP-GC fought anti-Assad rebels. Syrian government forces have besieged the district since July 2013. Limited supplies of food and water have entered the camp, causing severe malnutrition. An estimated 18,000 people, mostly Palestinians, remain inside. On April 1, ISIL infiltrated the camp, attacking the Palestinian anti-Assad group Aknaf Beit al-Madqis.

The Islamic State of Iraq and the Levant (ISIL) fighters stormed the camp on Wednesday, marking the group's deepest foray yet into Damascus. Palestinian officials and Syrian activists said they were working with rivals from the al-Qaeda affiliate in Syria, al-Nusra Front.

Al-Nusra said in a statement it is taking a neutral stance in the camp.

Chris Gunness, a spokesman for the UNRWA, the UN agency supporting Palestinian refugees residing in the camp, told the AP on Sunday that the agency has not been able to send any food nor any convoys into the camp since the current round of fighting started.

Gunness said: "That means that there is no food, there is no water and there is very little medicine."

He added 93 people have been evacuated from the camp so far.

Palestinian officials told Al Jazeera ISIL had control of about 60 percent of the camp and had placed snipers on top of buildings. Many bodies were lying on the streets uncollected, the official said.

Yarmouk, which houses thousands of Palestinian refugees and Syrians, has been shelled by government forces since fighting between Palestinian groups and members of ISIL began last week.

Over the weekend, about 2,000 people managed to flee Yarmouk as two exits were opened, Palestinian Liberation Organization spokesman Ahmed Majdalani told Al Jazeera on Monday. He said the operation was being conducted by Palestinian groups in coordination with the Syrian government.

About 18,000 civilians, including 3,500 children, are trapped in Yarmouk, according to UNRWA.

A myriad Syrian and Palestinian armed groups are active in Yarmouk, and the district has witnessed several rounds of deadly fighting between government forces and rebels.

The camp has been under government siege for nearly two years, leading to starvation and illnesses triggered by lack of medical aid.

As of February 2015, OCHA officially recognised 11 besieged areas in Syria with the estimate of 212,000 civilians living in them. A Syrian-American NGO, the Syrian Medical Society, estimates that the number of people living under siege is as high as 640,200.