The Yemeni government has accused the United Arab Emirates of landing around 100 separatist troops on a remote island in the Arabian Sea this week, deepening a rift between nominal allies in Yemen's war.
The UAE is one of the Arab countries fighting formally on behalf of Yemen's internationally recognized government against the Iran-aligned Houthi movement that controls the capital.
But the UAE has had a tense relationship with the government and has recruited thousands of fighters from a movement of southern separatists who have clashed with government troops.
Yemeni officials said around 100 separatist fighters had disembarked in civilian clothes on Monday from a UAE naval vessel on Socotra, the main island in a sparsely populated Yemeni archipelago in the Arabian Sea.
The island, part of Yemen but closer to the African coast than the Yemeni mainland, is a UNESCO world natural heritage site protected by the U.N. body for its unique flora and fauna.
It was not the first time the government of President Abd-Rabbu Mansour Hadi, which is based in the southern port of Aden, has complained about UAE troop moves on Socotra.
Last year the government accused the UAE of seizing the island when it unloaded tanks and troops there. Saudi Arabia, leader of the pro-Hadi Arab coalition, had to send troops to Socotra to defuse a standoff between Emirati and Hadi forces.
Two Yemeni government sources said on Wednesday that the UAE had trained a batch of 300 troops bound for Socotra in Aden last week, and sent more than 100 of them to the island on Monday.
Yemen's interior minister, reacting to reports that southern separatist troops were headed for Socotra, last week criticized the UAE and said it should concentrate on fighting the Houthis.
"I think our partnership with the coalition is the war against the Houthis and not sharing the administrations of the liberated territories," Ahmed al-Mayssari said in comments broadcast by Yemeni television channels.
The Emirati government and a spokesman for the Saudi-led coalition did not immediately respond to Reuters requests for comment. In previous statements, the UAE has denied Yemeni accusations that it is seeking control of the island.
The separatists say they have more than 50,000 fighters armed and trained by the UAE and aim to restore the independent state of Southern Yemen, which united with northern Yemen in 1990 at the end of a long war.
Clashes between Hadi's forces and the southern separatists are relatively rare but on Wednesday they fought each other in the southwestern al-Dhalea province over control of government buildings, a statement from Hadi's forces said.
The statement added Hadi forces left al-Dhalea after the clashes but were ambushed again on the way to Aden by the southern forces and "many were killed and wounded". It gave no further details.
The UAE has been at odds with Hadi because of his alliance with the Islamist Islah party. The UAE sees Islah as an offshoot of the Muslim Brotherhood, which it has designated as a terrorist organization.
DUBAI (Reuters) - by Aziz El Yaakoubi
(Additional reporting by Mohamed Ghobari in Aden)