Syrian regime air strikes continued on the Palestinian refugee camp Yarmouk on Sunday, prompting fresh concern about the humanitarian situation in the area.

Yarmouk over the past week has seen a dramatic increase of violence, as regime forces stepped up efforts against opposition forces said to be hiding in the camp, which is situated near the capital, Damascus.

Established in 1957 to house displaced Palestinians after the creation of the state of Israel, the camp was once home to roughly 200,000 refugees.

"Yarmouk and its inhabitants have endured indescribable pain and suffering over years of conflict. We are deeply concerned about the fate of thousands of civilians, including Palestine refugees, after more than a week of dramatically increased violence," Pierre Krahenbuhl, commissioner-general of UNRWA, the UN agency responsible for Palestinian refugees, said in a statement.

Yarmouk has been under siege since, which has caused hunger and illness among those who remained.

Aid groups have decried the situation of Palestinian refugees and Syrians in the area, accusing forces loyal to Bashar al-Assad of using missiles, barrel bombs and shillings, which have killed many civilians.

UK-based Action Group for Palestinians of Syria estimates that 60 percent of Yarmouk has been destroyed and many have fled the camp. UNRWA spokesperson Christopher Gunness told Al Jazeera there could be only a few hundred left.

The continued bombardment comes after the Syrian military on Saturday made their "most important" advancements through three neighborhoods near Yarmouk, witnesses said.

The areas include al-Hajar al-Aswad, al-Kadam and al-Tadamon, all found in the south of Damascus.

Regime forces and allied militias, including some Palestinian groups, launched a new offensive on the refugee camp and nearby areas in April.

Areas under attack

The offensive on Yarmouk comes after regime forces captured Eastern Ghouta, a Damascus suburb and one of the last opposition-held areas in the war-torn country.

Syrian regime forces allegedly used chemical weapons during a seven-week standoff that resulted in the army controlling the majority of the area that had been held by rebel forces since 2012.

In the northwest, Syrian and Russian warplanes are also bombarding the last major opposition-held city, Idlib, which is controlled by a coalition of opposition forces, including the Free Syrian Army and Ahrar al-Sham.

Idlib is housing an estimated two million people, including thousands of internally displaced who fled violence in other parts of the country.

French Foreign Minister Jean-Yves Le Drian has warned of a humanitarian disaster in the city.

Syria has been in a state of war since 2011 after authorities used lethal force to crack down on nonviolent protests against the Assad regime.

The conflict later escalated into a regional proxy war that has killed at least 500,000 people, displaced millions and created a refugee crisis.

Al-Jazeera