DUBAI (Reuters) - U.N.-sponsored Yemeni peace talks were struggling amid disputes over releasing prisoners, sources close to the talks said on Thursday, as local officials reported intensifying clashes and fresh air strikes despite a ceasefire.
Saudi-backed President Abd-Rabbu Mansour Hadi's representatives are demanding that their foes, the Iran-allied Houthi movement, release several senior officials.
Combat escalated between the warring sides on Thursday as Hadi loyalists seized a key military base from Houthi fighters in the central city of Marib, local officials and tribesmen said, where 15 people were killed from both sides.
Planes and gunboats from a Saudi-led military coalition also bombarded targets in northern Yemen, local residents said.
Yemen plunged into civil war last year when the Houthis seized the capital Sanaa and marched south, triggering the mainly Gulf Arab military intervention in March.
Peace talks began on Tuesday away from television cameras in Switzerland to try to end nearly nine months of conflict that have killed almost 6,000 people and displaced millions.
The sources said that direct talks between the two sides have been suspended since Wednesday evening, after the Houthis rejected demands to free senior officials, including Defence Minister Mahmoud al-Subaihi and Hadi's brother, Nasser.
Both Subaihi and Nasser Mansour Hadi, who was responsible for intelligence operations in southern Yemen have been held by the Houthis since March.
The Houthis say they are ready to free the prisoners once a permanent ceasefire is agreed, another source close to the talks told Reuters.
The sources said that instead of overseeing direct talks, U.N. special envoy to Yemen Ismail Ould Cheikh Ahmed was shuttling between the two sides trying to bridge differences.
Pro-Hadi fighters ejected the Houthis from the al-Mas camp, their last military base in the central desert province of Marib after two days of heavy combat.
Air strikes by the Saudi-led coalition also struck the northern Hajja province on the border with Saudi Arabia, residents said. They also said that gunboats struck Midi port, also in Hajja, near the Saudi border.
Both sides have been trading accusations over violating the ceasefire. On Wednesday, the Saudi-led coalition spokesman, Brigadier General Ahmed al-Asseri, accused the Houthis of committing some 150 violations since Tuesday and urged the United Nations to try to save the truce.
In a rare positive gesture on Wednesday, the Houthis and fighters from the so-called Southern Resistance, who are allied with Hadi, exchanged hundreds of prisoners early on Thursday, following delays by local tribesmen angry at the exclusion of relatives from the deal, an official involved in the swap said.
Fikri al-Mutaili, a southern commander, said the Houthis freed 265 residents of the former south Yemen while the Southern Resistance freed 300 Houthis, including 40 teenagers.
The deal was brokered by local tribal leaders and had been expected to reflect positively on the peace talks in Switzerland.
Reporting by Mohammed Ghobari and Mohammed Mukhashaf,; Writing by Yara Bayoumy and Noah Browning, editing by Sami Aboudi and Dominic Evans