Mohammed bin Salman, the Saudi crown prince, has thrown his weight behind the Yemeni government as it battles against a separatist group backed by Saudi Arabia’s allies in the United Arab Emirates (UAE).

The prince’s military coalition in Yemen fractured dramatically over the weekend as the Yemeni government and the southern separatists turned their guns on each other after years of fight side-by-side under Saudi leadership.

The intense fighting in the port city of Aden left 40 people dead as separatist forces, who seek an independent state in south Yemen, seized control of government buildings and fought against presidential guards.

Saudi jets carried out an airstrike in Aden in support of government troops and Prince Mohammed met with the Yemeni president, Abdrabbuh Mansur Hadi, on Sunday night in a show of support.

Mr Hadi’s office said the two men discussed the separatist “coup” against the government and “various other crimes against the sons of Aden”.

By Monday morning a tense calm appeared to have settled over Aden with no reports of fresh fighting between the two sides. Humanitarian groups warned that thousands of civilians were trapped in the firing line.