SANAA, Yemen (AP) — Heavy fighting in Yemen between pro-government forces and Houthi rebels has killed hundreds of people this month in several parts of the country, Yemeni officials and tribal leaders said Tuesday.

Yemen's civil war began in 2014 when the Iran-backed Houthis took control of the country’s north, including the capital Sanaa. A Saudi-led military coalition intervened against the Houthis on the side of the government the following year.

The Houthis have been attacking forces of the internationally recognized government in central Marib province in a bid to break through government defenses, officials said.

The Houthis claimed they seized control of a military camp in Marib. Government officials dismissed the claim, saying they repelled the Houthi attacks.

The officials said the Houthis shelled a hospital in Marib, prompting the evacuation of patients to another health facility.

Clashes were also reported in other areas, including the central province of Bayda, the southern province of Dhale and Jawf province, located along the border with Saudi Arabia, officials and tribal leaders said.

The rebels said Tuesday the Saudi-led coalition carried out at least a dozen airstrikes on rebel positions in Jawf and Marib. Fighting in the various provinces left over 500 fighters from both sides dead and wounded hundreds more, the rebels and government officials said.

The officials spoke on condition of anonymity because they were not authorized to brief the media, while the tribal leaders did so for fear of reprisals.

The fighting came despite a call by the U.N. secretary-general for Yemen’s warring parties to stop fighting and focus on reaching a peace agreement and countering the outbreak of the new coronavirus.

The arrival of the coronavirus in Yemen, which reported its first case earlier this month, threatens deeper and more widespread suffering in the Arab world’s poorest country.

The Saudi-led coalition announced a uniliteral, two-week cease-fire that went into effect April 9 to support the U.N.-led peace process and Secretary-General Antonio Guterres’ call for a cease-fire.

The clashes have continued, however, with both sides accusing the other of violating the cease-fire.

Despite relentless Saudi airstrikes and a blockade of Yemen, the war has ground to a stalemate. The conflict has killed over 10,000 people and created the world’s worst humanitarian crisis, leaving millions suffering from food and medical care shortages and pushing the country to the brink of famine.