Syrian elite forces aided by pro-Iranian militias stepped up an offensive on Tuesday against a rebel enclave in a southwestern pocket bordering Jordan and Israel, according to residents, military, and opposition sources.

Fighting escalated earlier this week after the collapse of a Russian peace plan meant to avert an all-out offensive against Deraa al-Balaad, the core of the city of Deraa that has defied state authority since surrounding Deraa province was recaptured by President Bashar al-Assad's forces in 2018.

Witnesses and military sources said dozens of improvised missiles were fired into Deraa al-Balaad by the Syrian military's pro-Iranian Fourth Division, which is backed by Iranian-financed local militias.

A halt to fighting was announced after Russian generals offered a new plan that appeared to meet some of the rebel demands to involve the Russian military police in patrolling the enclave while allowing for the first time a Syrian army security presence in the stronghold.

Rebels said they accepted the plan while the army said it would give its response by Wednesday to the deal that also allows the Syrian and Russian flags to be raised in the opposition bastion but gives Moscow's guarantees that Iranian-backed army units cannot act with impunity.

Army sources said Iranian-backed troops that have encircled the urban rebel enclave for the last two months and which brought forward reinforcements on Monday would be withdrawn under the deal.