Ban Ki-moon, the UN secretary-general, has said that he believes al-Qaeda was responsible for last week’s bombings in Damascus, the Syrian capital, that left more than 50 people dead.
"A few days ago there was a huge, serious, massive terrorist attack. I believe that there must be al-Qaeda behind it. This has created again very serious problems," Ban said on Thursday.
At least 55 people were killed and 372 others were wounded in blasts in Damascus on May 10, in the deadliest attacks in the Syrian capital since an uprising against President Bashar al-Assad began early last year.
Ban also noted that there have been two attacks against unarmed UN monitors trying to reduce the violence in the country.
There are 257 unarmed UN monitors in Syria to observe an unravelling five-week-old truce negotiated by UN-Arab League peace envoy Kofi Annan.
"The deployment of monitors has some dampening effect, the number of violence has reduced but not enough, not all the violence have stopped," Ban said while addressing youth group at UN headquarters in New York.
"We are trying out best efforts to protect the civilian population."
The UN chief said at least 10,000 people had been killed in the conflict.
Damascus says that it is facing a "terrorist" conspiracy funded and directed from abroad.
Earlier this month, Syria sent the UN the names of 26 foreign nationals it said had been apprehended after coming to fight in the country.
It described 20 of those as members of al-Qaeda who had entered the country from Turkey.