Saboteurs on Thursday threw two Molotov cocktails at the Arab League headquarters in central Cairo, with no reports of casualties or serious damage, an Arab League source told AFP.
"At dawn this morning, there were two Molotov cocktails thrown into the Arab League building. There were no casualties, and only minor damage was caused to one of the air conditioning units," the source said.
Another source close to the Arab League said the 22-member body had received several threats by telephone from members of the Libyan and Syrian communities.
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He said there had been "several phone calls" expressing anger at the league's response to the conflicts in both countries, but refused to provide further details.
The Arab League headquarters are located in Cairo's Tahrir Square, the epicentre of protests that toppled Egyptian president Hosni Mubarak in February.
Protest movements have rocked the Arab world in recent months, with two uprisings in Tunisia and Egypt ousting their long time leaders.
In Libya, thousands have died as rebels, supported by a NATO campaign, have fought to overthrow leader Moamer Kadhafi, while Syrian protesters have faced a deadly crackdown by the regime of President Bashar al-Assad and hundreds been killed.