Syrian forces have captured the largest town in Eastern Ghouta, effectively splitting the rebel-held enclave in three, a monitor told Al Jazeera.

The Syrian Observatory for Human Rights (SOHR) said on Saturday that government forces had captured the town of Mesraba, which lies 10km east of Damascus, and had begun advancing into its surrounding farms.

The UK-based monitor told Al Jazeera that Eastern Ghouta had been divided into three parts - Douma and its surroundings, Harasta in the west, and the rest of the towns further south.

Syrian state television reported earlier that army operations were intensifying in the central part of Eastern Ghouta, with opposition activists also reporting that roads connecting the towns were covered by army fire.

The government's latest offensive on Eastern Ghouta, which began on February 18, has seen 1,002 people killed, according to the Observatory. The figure includes 215 children and 145 women.

The Syrian American Medical Society (SAMS) told Al Jazeera that at least 49 people, including 14 women and 10 children were killed on Friday, and a further 200 wounded.

President Bashar al-Assad and Russia say the campaign is needed to end rebel rule over the area's civilians.

Aid agencies have struggled to deliver aid to the besieged enclave, bringing in only a portion of the amount they wanted.

The Syrian government's offensive follows a pattern of previous assaults on rebel strongholds, deploying massive air power and tight sieges to force rebel fighters to accept "evacuation" deals.

These involve rebels surrendering territory in exchange for safe passage to opposition areas in northwest Syria, along with their families and other civilians who do not want to come back under Assad's rule.

Opposition evacuated

In a surprise move, several members of Syria's armed opposition have been evacuated from rebel-held Eastern Ghouta late on Friday, sources told Al Jazeera.

The evacuation came as the Syrian army intensified its operations in the central part of the besieged Damascus suburb, state television reported on Saturday.

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Jaish al-Islam, one of the main rebel groups in Eastern Ghouta, announced it had agreed to the evacuation of several Hay'et Tahrir al-Sham fighters - previously part of al-Qaeda-linked al-Nusra Front - who were detained by the group in Eastern Ghouta.

According to Syrian state media, 13 fighters were evacuated with their families through the al-Wafeedin passage and bussed to Idlib province.

The agreement for the evacuation was reportedly reached with the help of the United Nations and several international entities, in addition to civil society members.

The evacuation deal came after Jaish al-Islam sent a letter last month to the UN vowing to facilitate the evacuation of the former al-Qaeda members.

Eastern Ghouta, which is home to about 400,000 people, has been under siege by the government ever since armed opposition groups took control of it in mid-2013.