Saudi shells hit an international humanitarian aid office in northern Yemen on Thursday, killing five Ethiopian refugees and wounding 10, a local official said.
Artillery fire and airstrikes hit the town of Maydee along Yemen's border with Saudi Arabia in Hajja province, a stronghold of the Iran-allied Houthi militia that a Saudi-led Arab alliance has been bombing for eight weeks.
Saudi forces and Houthi militiamen exchanged heavy artillery and rocket fire, and Arab airstrikes hit Houthi positions inside Yemen on Thursday, violence that may complicate plans for U.N.-backed peace talks set for May 28 in Geneva.
U.N. chief Ban Ki-moon on Wednesday announced the Geneva talks between the warring Yemeni parties, and both Hadi's government and the Houthis have indicated they will attend.
The Saudi-Yemen frontier has in some cases become a frontline between the two sides, and the Houthis' Al Masira TV channel broadcast footage on Wednesday it said showed its fighters entering a Saudi border post after being fired on by Saudi tanks and helicopters.
"[Saudi] military hardware was deployed, but after a few moments they vanished, fleeing the Yemeni advance attacking them," the channel said.
There was no immediate Saudi confirmation.
Tribal sources along the Saudi-Yemeni border said that more than 15 Houthi fighters and at least one Saudi officer were killed in intense clashes on Wednesday.
Airstrikes in Aden
Residents and local fighters opposing the Houthis said airstrikes hit a southern air base controlled by the militia and their positions outside the southern city of Aden on Thursday.
Tribal and militia fighters in Yemen's south support the Arab campaign and back president Abd-Rabbu Mansour Hadi, who lives in exile with his government in Saudi Arabia.
An Iranian-aid ship bound for the Houthi-controlled Red Sea port of Hodaida in Yemen appeared to be headed to Djibouti for inspection Thursday, ship-tracking data showed.
Iran's Deputy Foreign Minister Hossein Amir Abdollahian said the ship would submit to U.N. inspections in the Horn of Africa country, avoiding a potential regional showdown between Riyadh and Tehran.
The Iran Shahed had been escorted by Iranian warships, and Saudi-led forces have enforced inspections on vessels entering Yemeni ports to prevent arms supplies from reaching the Houthis.
Saudi Arabia and its Sunni Muslim allies believe the Houthis are a proxy for the influence of their arch rival, Shi'ite Iran, in the Arabian Peninsula.