Civilians killed in bus explosion in Syria's Turkish-controlled Afrin

Three civilians were killed when a bus exploded in the northern Syrian city of Afrin on Sunday, on the first anniversary of the Turkish intervention in the Kurdish-majority region, a war monitor said.

Nine other people, including fighters, were wounded in the explosion, the head of the Britain-based Syrian Observatory for Human Rights, Rami Abdel Rahman, told AFP.

Turkish troops and allied rebel groups seized the Afrin region from Kurdish forces in March last year after a two-month air and ground offensive.

"The explosion is the result of a bomb that was placed in a bus in the centre of Afrin," Abdel Rahman said.

It was not immediately clear who was behind the blast, the second to rock Afrin since December 16 when a car bomb killed at least nine people, including five civilians, near a pro-Turkey rebel post in the city.

That explosion came after Turkish President Recep Tayyib Erdogan threatened to launch a new offensive against the Kurdish People's Protection Units (YPG) in Syria.

Turkey accuses the YPG of being "terrorists", but the Kurdish militia also forms the backbone of a US-backed alliance fighting the Islamic State group in Syria.

The bomb blast came as fatalities were reported following a "huge explosion" near a military intelligence office in Damascus on Sunday, with state TV describing the attack as a "terrorist act".

"The explosion took place near a security branch in the south of the city. There are some people killed and injured but we could not verify the toll immediately," the minority told AFP.

It was unclear if the blast was caused by a bomb that was planted or a suicide attack, according to the monitor, which relies on a network of sources inside the country. However, shooting was reported following the explosion. 

Syrian state television earlier reported that a blast had been heard around the southern highway in Damascus. 

"First reports suggest a terrorist act," the broadcaster said, although it fell short of providing further information or details on the incident. 

Syria is locked in a civil war that has killed more than 360,000 people by official counts suspended in 2014, and much more by unofficial counts, and displaced millions since a brutal crackdown on anti-government protests in 2011 spiralled into full conflict. 

With key military backing from Russia, President Bashar al-Assad's forces have retaken large parts of Syria from rebels and jihadists, and now control almost two-thirds of the country.

The Syrian regime in May reclaimed a final scrap of territory held by the Islamic State group in southern Damascus, cementing total control over the capital for the first time in six years.

Observatory chief Rami Abdel Rahman said that Sunday's blast appeared to be the first attack in Damascus in over a year. 

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