I WAS in a car heading south towards Beirut when news of yesterday's bombing at the Iranian embassy broke.

It came in a telephone call from a colleague of my Lebanese driver. Knowing the area of the attack well, my driver insisted it was most likely a car bomb rather than a rocket attack as was originally suspected.

The district, he told me, was under strict security control of Hezbollah, the Lebanese Shia militant group, and the chances of any rocket attack being launched there were negligible. His instincts proved correct in what was a double suicide strike by bombers using a motorcycle and car.

On arriving in the city centre, emergency vehicles were still sweeping through Beirut's streets. Lebanon has seen a spillover of the war in neighbouring Syria lately. Split along sectarian lines and divided by opposition to and support for Bashar al Assad's regime in Syria, there are more frequent clashes between these rival groups. Nowhere is this more obvious than in Tripoli, Lebanon's second largest city.

It was just as we were passing through Tripoli yesterday that we heard of the Beirut bombing. Along a main highway that winds along Tripoli's bustling port road, residents in rival neighbourhoods have been engaged in deadly escalating clashes. These neighbourhoods are ground zero in Lebanon's slice of the Syrian civil war, where exchanges of shell and sniper fire are increasingly common. After the Lebanese government announced a new security plan last month, Lebanese Armed Forces were deployed. In all there have been 18 major clashes in Tripoli over the past two-and-a-half years, mirroring the fighting in Syria.

In the wake of yesterday's bombing and as the Syrian regime launches a new offensive just over the border near the strategic town of Qara, Lebanon is bracing itself for another round of sectarian violence. The Syrian civil war is beginning to have real impact on this country.