The humanitarian situation on the outskirts of the capital of Syria, Damascus, is worsening as government forces continue their siege on the opposition stronghold of Eastern Ghouta.

In the seventh day of fighting, the UK-based Syrian Observatory for Human Rights said on Thursday that the infighting between rebel groups Jaish al-Islam, the al-Rahman Corps and the al-Qaeda-linked Levant Liberation Committee (Hayat Tahrir al-Sham) has killed at least 143 people, including 13 civilians.

Jaish al-Islam reportedly asked civilians to stay put and not leave their homes and also asked rival groups to surrender and hand themselves in, the Observatory said.

The Damascus suburb has been repeatedly targeted by government forces, and residents now fear they may be forced to leave, sources in the area told Al Jazeera.

"Life has turned into a tragedy here. Prices are rising. Just to give you an idea; a kilogramme of sugar has doubled over the last few days." Abu Ibrahim, a resident of Douma in the northern part of Ghouta said.

"These are tough times for us. The opposition is losing ground and the siege is getting worse and civilians pay the price. I cannot see a solution," Abu Yazan, a student in the town said.

It is not only the prices of food that has been affected. Medical workers say the health situation in the area is critical.

"The government blockade must be immediately lifted and medicine must be allowed into besieged areas. The price of medication has to be regulated so we can maintain standard pricing," Bayan Al Shami, a pharmacist, said.

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Eastern Ghouta, which has been partially besieged by the Syrian government since 2013, has an estimated population of 400,000, according to a report by a Netherlands-based monitor.

In 2013, the Syrian government banned civilians from going into or out of the enclave, allowing only some food deliveries.

The area is made up of 22 communities and has seen Russian and Syrian air attacks on markets, schools, and hospitals in many of them.

Ghouta has been a stronghold for major rebel groups, including Jaish al-Islam, al-Rahman Corps and the Levant Liberation Committee during much of the six-year conflict.

The Netherlands-based monitor Siege Watch said at least 913,575 civilians live in besieged areas across Syria, while 1.3 million live in "Watchlist" areas under threat of complete siege.