Clashes were underway Wednesday along several front lines in Yemen, claiming at least 42 lives and undermining a day-old cease-fire and peace talks between the internationally recognized government and Shiite rebels taking place in Switzerland.

The U.N.-brokered talks that began Tuesday were meant to give Yemen's warring factions a chance to find a solution to the conflict that has engulfed the Arab world's poorest country.

At the same time, an agreed-on cease-fire went into effect on the ground, meant to last a week. But as fighters on both sides ignored the truce, expectations for the negotiations were low.

In the capital, Sanaa, a high-profile official from the rebels, also known as Houthis, warned on Wednesday that it will not be possible to continue the talks unless the cease-fire holds.

According to security officials, fighting was underway for a second day Wednesday in the provinces of Ibb, Bayda, Marib, Jawf, and Taiz. In the besieged city of Taiz, shelling by Houthis killed six civilians, said the officials who are neutral in the conflict and spoke on condition of anonymity because they were not authorized to talk to reporters. The officials also said the 42 were killed since the cease-fire started.

Yemen's conflict pits the rebels and army units loyal to former President Ali Abdullah Saleh against forces of the internationally recognized government, allied with southern separatists, religious extremists and other militants. The government is backed by a Saudi-led coalition.

According to U.N. figures, the war in Yemen has killed at least 5,884 people since March, when the fighting escalated after the Saudi-led coalition began launching airstrikes targeting the rebels.

Previous efforts to end the violence have ended in failure, as the government insisted the Houthis comply with a U.N. resolution that requires them to hand over weapons and withdraw from territory they captured over the past year, including the capital, Sanaa. The Houthis have demanded the country's political future be decided through negotiations.

In the past, the rebels have said they are willing to honor the U.N. resolution but did not specify to whom they would hand over weapons and territory. Yemen's civil war has also divided the armed forces, which have units loyal to ousted president Saleh, a Houthi ally, and others who answer to the internationally recognized government of President Abed Rabbo Mansour Hadi.