A fierce fighting between the government forces and armed tribes loyal to opposition leader Sheikh Sadiq al-Ahmar erupted on Tuesday with huge explosions and heavy gunshot exchange, breaking down a ceasefire stroke earlier the week between the two sides, a security official said.

The fighting has been going on since Monday evening, in which armed tribes of Sheikh al-Ahmar, the chieftain of powerful Hashid tribes' confederation, re-controlled the Ministry of Local Administrative, two days after they informally stroke a truce with the government forces and handed the ministry over to a mediation committee.

"Government forces are shelling all hideouts of al-Ahmar's gang after the later broke down the ceasefire deal by opening fire on government buildings and policemen," the official said on condition of anonymity.

"In Dhahban area, near the state television north of capital Sanaa, security forces shelled a building of Shiesh Aiyeedh Hussein who along with his armed tribes is loyal to Sadiq al-Ahmar and involved in opening fire on the military camp in the area," he said.

"The government forces were also shelling many hideouts of al- Ahmar's fighters in the capital Sanaa, including Tunisia Street in west, in Marib crossroads in eastern Sanaa and the main stronghold compound of al-Ahmar in Hassaba district in downtown Sanaa," he added.

Meanwhile, the Defense Ministry's website reported that the armed tribes of al-Ahmar controlled the building of the headquarters of the ruling General People's Congress party in Hassaba, which is confirmed by an official of al-Ahmar's office, according to local opposition media.

The official accused government forces of breaking down the truce deal, saying forces of Sheikh al-Ahmar therefore took control of a Hassaba police station and the state-run water corporation, which is close to the state-run Television and Radio Corporation.

Another security official of the Interior Ministry said the house of al-Ahmar in Hassaba, the key stronghold of al-Ahmar's fighters, has been shelling by missiles.

On Sunday evening, fighting took place near al-Ahmar's house in Hassaba, just hours after armed tribesmen of opposition tribal leader handed over the Ministry of Local Administrative to a mediation committee based on a cease-fire deal to end the last week pitched street battles.

In the deal, which was informally stroke on Saturday and came into effect on Sunday, al-Ahmar stipulated the withdrawal of government forces from around his home in order to hand over the rest of the government building seized by his armed tribesmen last week.

Both rivals are trading accusations of breaching the fragile ceasefire deal, igniting non-stop heavy street battles in downtown the capital between government forces and fighters of al-Ahmar who sided with the four-month-long protests demanding an immediate end to the 33-year rule of President Ali Abdullah Saleh.