About 200 fighters have been killed in fresh clashes near the strategic Yemeni city of Marib, military and medical sources said Tuesday, as the seven-year war witnesses a surge in violence.

More than 125 Huthi rebels were killed in airstrikes by the Saudi-led coalition and clashes with pro-government forces in Shabwa and Al-Bayda provinces, bordering Marib, medical sources told AFP.

The pro-government Giants Brigade, backed by Saudi Arabia and the United Arab Emirates, also lost 70 fighters, Yemeni government sources said. The clashes took place over the past 24 hours.

The Saudi-led coalition has been fighting for nearly seven years in support of Yemen's government against the Huthis, in a conflict that has displaced millions and created the world's worst humanitarian crisis, according to the United Nations.

As hostilities escalated, the rebels on Monday said they had seized a military ship flying a United Arab Emirates flag. The coalition insisted it was carrying medical supplies.

In September, the rebels intensified their efforts to take Marib, a provincial capital which is the government's last northern stronghold.

Recent weeks have seen another spike with Saudi airstrikes on rebel territory multiplying, while the Huthis have ramped up missile and drone assaults on the kingdom.

Thirty-nine wounded arrived at Shabwa's Ataq hospital in just one day on Sunday, according to a Medecins Sans Frontieres team that arrived in late December.