It's been reported that more than 40 people have been killed in twin suicide bombings in the Syrian city of Homs.

The Syrian Observatory for Human Rights - which documents violence in the country - says the attacks hit the headquarters of state security and military intelligence.

Speaking to AFP news agency, The Syrian Observatory director Rami Abdel Rahman said "There were at least six attackers and several of them blew themselves up near the headquarters of state security and military intelligence."

Militants with guns and suicide bombers killed the head of military security and 29 others at one of its headquarters, and 12 more people at a branch of state security.

The Syrian Observatory have said that it's not yet clear who's responsible for the bombings. 

The twin attacks took place in the heavily guarded Ghouta and Mahatta neighbourhoods in the city. 

Homs has been under the full control of the government since May 2014 when rebels withdrew from the city centre under a UN-brokered truce.    

The city has seen repeated bombings since then. Twin attacks also killed 64 people early last year.