Riyadh, Sep 6 (AFP) Saudi Arabia on Thursday issued a stern warning to Yemeni separatists who have seized key parts of the south, saying any attempt to destabilise Yemen amounted to a threat to the kingdom.

In its first strongly worded response to the crisis threatening to splinter Yemen, Riyadh demanded separatists return captured military and civilian facilities to the Saudi-backed government while renewing calls for dialogue.

"The kingdom stresses that any attempt to destabilise Yemen is a threat to its security and stability...and will be dealt with firmly," the official Saudi Press Agency said.

"It also affirms its...position that there is no alternative to the legitimate government in Yemen and that it does not accept any attempts to create a new reality in Yemen by using force or the threat of force."

Last month, fighting between the separatists and supporters of the government opened a new front in Yemen's complex war.

The Security Belt Forces -- dominated by the secessionist Southern Transitional Council -- took control of the southern city of Aden, which has served as the government's base since it was ousted from the capital Sanaa by Huthi rebels in 2014-15.

The clashes between separatists and government forces -- who for years fought on the same side against the Huthis -- have raised fears that the country could break apart entirely.

"Saudi Arabia...expresses its complete rejection of the recent escalation and...the failure to respond to its previous call to move towards dialogue," SPA said.

"The kingdom affirms...the need to restore the camps and headquarters of the military and civilian institutions of the legitimate government. The warring parties...must take part in dialogue in the kingdom immediately."

Yemen's government on Wednesday ruled out talks with separatists, saying it will talk only with their main backer, the United Arab Emirates.

The UAE has trained and supported secessionists who seek an independent southern Yemen, despite being a key pillar in a Saudi-led military coalition backing the government against Iran-aligned Huthi rebels.

The Yemeni government has accused the UAE of launching air strikes against its troops in Aden, while the Emirates says it was acting in self-defence against "terrorist militias" threatening the Saudi-led coalition.

The coalition intervened in Yemen in March 2015 as the Huthi rebels closed in on Aden, prompting President Abedrabbo Mansour Hadi to flee into Saudi exile.

The conflict has since killed tens of thousands of people -- most of them civilians -- and driven millions more to the brink of famine in what the United Nations calls the world's worst humanitarian crisis. (AFP)

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