Government troops thwarted an attack by Shiite rebels in the capital of the restive north-western province of Saada on Sunday after a shaky truce collapsed, a military source said, according to dpa. The army fought back the rebels, known as Houthis, and "inflicted huge losses" on them after they attacked Saada city from three directions at dawn, the unnamed source said in a statement posted on the Defence Ministry's website. "Elements of rebellion and terrorism tried to take advantage of the ceasefire and the halt of military operations ... to achieve gains on the ground," the source said. The source did not give a casualty toll among the rebels or the army during Sunday's confrontations in Saada, some 240 kilometres north of the capital Sana'a. Local sources in Saada said around 150 rebels and at least two soldiers were killed. The rebels denied the reported attack against Saada city. "Reports about confrontations in the outskirts of Saada city and our attempt to march into it are not true," said a statement by the media office of the rebel leader Abdul-Malik al-Houthi. It said the army claims were made to "justify the (army) aggression that is going in various districts." The group accused the army of violating the truce by bombarding 23 villages in Saada and the neighbouring province of Amran with artillery and rockets overnight Saturday and Sunday morning. Authorities declared a ceasefire in fighting with the rebels in order to secure the passage of humanitarian aid to tens of thousands of people stuck in the fighting areas on the borders with Saudi Arabia. The truce that took effect at midnight Friday and lasted only for a few hours, was announced in response to appeals from international relief agencies, official media said. The ceasefire was conditional on the rebels complying with five terms, including their withdrawal from areas they control and release of soldiers captured during the fighting. Among the conditions were the rebels' compliance with the constitution and their surrender of military equipment seized from the army. This was the second truce declared by the government since the army launched its latest offensive on Houthi bases on August 11. It is the latest flare-up in the fighting that has raged on and off since the Houthis' revolt began in mid-2004. On September 4, authorities announced a truce to allow access for humanitarian aid to civilians displaced by the fighting in Saada and Amran provinces. The first truce collapsed three hours after it took effect, and both sides traded blame for breaking it. Hundreds of insurgents, troops and civilians have been killed and around 150,000 people were forced to leave their villages during the past five weeks, according to unofficial estimates. Authorities accuse the Shiite group of seeking to restore the rule of the Zaydi royal family, which was toppled by a republican revolution in 1962. The Houthis say they are in revolt against government corruption and the Yemeni alliance with the United States.