Violence has killed 36 people and wounded 185 since Sunday

SANAA, Yemen－The embattled Yemeni prime minister was preparing to flee the country on Tuesday for Saudi Arabia after separatists seized the area around the presidential palace in the southern port city of Aden in fierce battles overnight, security officials said.

In a separate development, suspected Islamic militants attacked a checkpoint in the country's southern Shabwa province on Tuesday, killing at least newly-recruited 15 soldiers there. No group immediately claimed responsibility for the attack but Yemeni troops have claimed victory over al-Qaida in the province.

According to the security officials, fighters loyal to the so-called Southern Transitional Council fought all way to the gates of the Palace of Maashiq in the district of Crater in Aden, forcing President Abed Rabbo Mansour Hadi's troops to abandon their positions. The officials said Hadi's prime minister and several Cabinet members would leave Yemen imminently for Riyadh.

The palace is the seat of Yemen's government. The separatist forces did not enter the palace itself and were stopped by Saudi Arabian troops who have been guarding the palace for the past months.

However, a senior government official said that Prime Minister Ahmed Obaid Bin Daghar and several ministers remained inside the palace and that the separatists had not seized the palace itself.

The official declined to say whether the prime minister was to leave Aden. The security officials and the government official spoke on condition of anonymity under regulations.

The fighting in Aden first erupted on Sunday, when a deadline issued by the separatists for the government to resign expired. Hadi, who has been in Saudi Arabia for most of the war, has described the separatists' action as a "coup".

The violence in Aden has killed at least 36 people and wounded 185 since Sunday, according to the International Committee of the Red Cross.

It has also exposed deep divisions within the alliance between Hadi's government and the Saudi-led coalition. The two are fighting against Yemen's rebels, known as Houthis, who are in control of the country's north.

The war started in 2015 when the Houthis captured much of the northern region after overrunning the capital, Sanaa. The warring parties have been locked in a bloody stalemate for most of the war, which has killed over 10,000 civilians and displaced 2 million, with the United Nations saying that Yemen is facing the world's worst humanitarian crisis.

The unfolding events in Aden have thrown Yemen into deeper uncertainty.

The US State Department has expressed concern and called upon all parties to "refrain from escalation and further bloodshed". Washington backs the Saudi-led coalition.

France also expressed concerns on Monday, calling rival factions to "engage in dialogue" so as to not "hinder the resolution of the crisis", the country's Foreign Ministry said.

Amid reports of armed conflict in Aden, a UN spokesman said on Monday that while there is concern about the clashes and closing of the airport, all of its staff members are "safe and accounted for".

"We have been concerned about the situation," Farhan Haq, deputy chief UN spokesman told reporters at UN Headquarters. "We have been calling on all sides to respect international humanitarian and Human rights law. We continue to monitor the security situation in Yemen."

Reuters-Xinhua-AP