Rebels in Burundi have fired mortar bombs on the capital, Bujumbura, hitting the residence of the Vatican envoy.

There are no reports of casualties from the attack, the latest in a series of clashes between rebels and government forces over the past week.  The fighting has killed at least 33 people.

Witnesses say the rebel National Liberation Forces (FNL) launched the mortar attack late Tuesday from hills outside the capital.

One mortar struck the home of Vatican envoy, Archbishop Paul Richard Gallagher.  The envoy is said to be traveling abroad.

Earlier Tuesday, the Burundian air force shelled rebel positions in the Rukoko marshes, about 20 kilometers north of the city.

The FNL rebels signed a peace agreement with the government in July 2006, but the accord was broken a year later. 

Burundi is trying to emerge from a 13-year civil war that killed more than 250,000 people.

Late last week, U.N. Secretary-General Ban Ki-moon said he was gravely concerned about the recent fighting in Burundi.  He urged the immediate cessation of hostilities.

Some information for this report was provided by AFP, AP and Reuters.