SANA'A: Yemen's president has fired a government minister for failing to persuade an expanding protest movement to end its monthlong challenge to his 32-year rule over one of the most impoverished and volatile corners of the Arab world. Scattered clashes broke out across Yemen Monday, killing three soldiers in the north, as military forces were deployed to check nationwide protests demanding the resignation of Saleh. Almost 40 protesters were injured when police opened fire to disperse demonstrations across the country, officials said. Two soldiers and an officer were killed as clashes broke out in the northern Al-Jawf province, Yemen's state news agency Saba said. Fighting intensified after protesters stormed a municipal building. Security forces fired on them, wounding 10, but could not stop them seizing the building, a local official said. In the central Maarib province, where several oil and gas fields of international companies are located, a man stabbed governor Naji Zayedi, critically wounding him as he and police tried to break up a crowd of thousands at a sit-in. “Members of the opposition stabbed the governor and wounded three others as security tried to stop protesters from inciting chaos,” a local official said. With no sign his opponents will accept anything less than his ouster, Saleh has filled the streets with armed supporters in an increasingly violent crackdown. Soldiers and armored vehicles tried to cut off an area in Sana'a, where around 20,000 anti-government supporters have been camped out for weeks. The opposition gained its own support Monday from striking workers, as well as from university professors and a growing number of powerful tribal chiefs turning against Saleh. In a sign of his frustration, Saleh on Sunday fired the government minister in charge of trying to engage his opponents in dialogue, Hamoud Al-Hattar, and replaced him with another Cabinet minister. In the streets of the capital Monday, police and plainclothes security remained locked in a standoff with protesters camped out in a square near Sana'a University. Amin Al-Ukeimi, a leader of the powerful Bakeel tribe, announced Monday that he is joining the protesters in Sana'a and supported their demand to bring down the regime. Mohammed Al-Houri, an undersecretary at the Planning Ministry, also announced his resignation from the party. The western part of the capital was paralyzed Monday by a strike called by trade unions to protest the government's harsh handling of the demonstrators and to demand higher wages. Clashes with protesters also broke out beyond the capital Monday in the southern provinces of Aden, Hadramawt, Taiz and Hudaydah, and in Jawf in the northeast. In Taiz, police tried to disperse demonstrators with gunfire and tear gas, injuring three people.