The Yemeni government said on Thursday that the Shiite rebels killed 20 people, including six policemen, in an ambush on a convoy carrying food supplies for government forces stationed in the north, Xinhua reported.
"Fourteen of those killed were pro-government tribesmen of al-Majaz directorate in the northern Saada province where they were helping the authorities to enforce law and stability in the troubled area," said a statement posted on the Defense Ministry's website.
Meanwhile, the Interior Ministry website said "such horrid criminal act, which took place on Wednesday, has no meaning, but will impede governmental efforts to bring peace to Saada province."
In its statement, the Interior Ministry accused the Shiite rebels of having committed "635 ceasefire violations till now since a truce agreement took effect on Feb. 11, including shooting dead military and security personnel and re-establishing checkpoints in the area."
There was no immediate reaction by the rebels to the government accusation.
The truce-breaching incident came two days after the Yemeni president and the Qatari emir agreed to reactivate the Doha peace agreement between the government and the northern Shiite rebels mediated by Qatar.
According to the agreement signed in early 2008, both sides should stop military operations and the rebels should hand over their military equipment to the authorities, respect the sovereignty of the central government in all Yemeni territories and establish a political party to replace the armed movement.
The Yemeni government declared the Doha peace agreement dead on Aug. 26, 2009, accusing the Shiite group of violating the agreement, and the sixth round of war between the two sides erupted that month.
On Feb. 11, the government and the Shiite rebels struck another ceasefire agreement to end their conflict. However, both sides repeatedly traded accusations against each other over truce breach.
Yemen has witnessed sporadic battles since 2004 between government troops and the Shiite Houthi rebels whom the government accused of seeking to re-establish the clerical rule overthrown by the 1962 Yemeni revolution which created the Yemeni republic.