Islamist-led rebels in Syria captured the strategically crucial city of Hama on three sides, both the militants and the Syrian government said on Thursday.

"Over the past few hours, with the intensification of confrontations between our soldiers and terrorist groups... these groups were able to breach a number of axes in the city and entered it," the army said, adding that it had withdrawn from the city to prevent urban combat and the civilian death toll associated with it.

The UK-based Syrian Observatory for Human Rights said that the rebels were able to make significant advances in the last 24 hours, despite the government sending "large military convoys to Hama" and the surrounding area.

They added that the Syrian army has been joined by Russian and Iranian officers, as both countries have been longtime allies of Syrian President Bashar al-Assad.

State news agency SANA confirmed that the government was waging "fierce battles" across Hama province, led by "joint Syrian-Russian warplanes."

German news agency DPA said that award-winning Syrian photographer Anas Alkharboutli was killed in one of the airstrikes on Hama.

What's the current situation in Syria?

After capturing Hama, rebels said they were preparing to keep marching south towards Homs, a city that links the capital Damascus to the north and coast.

On Thursday, Assad's forces shot down two "enemy" drones over Damascus, state news agency SANA reported.  

"A short time ago, our air defenses confronted enemy drone aircraft in the skies over Damascus," the statement from a military source said, adding that "two aircraft were shot down, without any human or material losses."  

China, meanwhile, urged its citizens to leave Syria "as soon as possible."

"Currently, the situation in northwestern Syria is intensifying, and the overall security situation is deteriorating further," the Chinese embassy said in a message on its WeChat account. 

It advised Chinese citizens in the country "to make use of available commercial flights to return home or leave the country as soon as possible."

Surprise offensive

The latest violent clashes follow a surprise offensive led by Hayat Tahrir al-Sham (HTS) extremist rebels and their allies last week. The group quickly captured the city of Aleppo, which has never been out of government hands in over a decade of civil war in Syria.

Control of Hama is considered strategically significant because the city connects Aleppo with the capital Damascus. Moreover, although Hama city was home to large protests against Assad's rule in 2011, the province is home to a great number of Alawites. This is the community from which Assad hails and provides a strong base of support for the president.

The United Nations has said that hundreds of people, mostly fighters, have been killed in the latest flare-up of violence in Syria, and some 115,000 have had to flee their homes.

Who is fighting in Syria?

In 2011, Assad led a brutal clampdown on Arab Spring protests calling for an end to his authoritarian rule, leading to the outbreak of the Syrian civil war.

Parties to the conflict have changed over the years, and have included groups that ran the ideological gamut from moderate rebels who sprang out of the protest movement to the extremist "Islamic State" (IS) group.

Following the defeat of IS, things were relatively quiet for a time.

The most recent spate of attacks has been led by HTS, an al-Qaeda offshoot that has pro-Turkish leanings. Turkey has long been opposed to Assad. 

HTS is based out of Idlib, one of the last rebel bastions in Syria.

Supporting Assad both diplomatically and at times militarily over the years has been Russia and Iran, who continue to do so now. Iraqi militias have also joined Syrian government troops on the battlefield.

es/rc (AFP, dpa, Reuters)