Aidarus al-Zubaidi, vice president of the Presidential Leadership Council based in the southern city of Aden, told AFP the aerial barrage alone was not enough to deter Huthi attacks on merchant ships in the Red Sea.

"An international and regional alliance is necessary to secure international navigation in the Red Sea," Zubaidi said in an interview at the World Economic Forum in Davos, Switzerland.

Zubaidi heads the secessionist Southern Transitional Council, which wants to split the country back in two, reversing its 1990 unification.

He said a Saudi-led military intervention launched in support of the government in 2015, which has also involved air strikes, had been "insufficient" to deter the Huthis.

"Ground forces must be supported on the ground, and these forces belong to the legitimate government," he said.

"These forces are the ones who can achieve a victory on the ground, because strong strikes without ground operations are useless."

Zubaidi's colleagues in the Presidential Leadership Council, which unites various anti-Huthi groups, could not immediately be reached for comment.

Last month, Yemen's warring parties committed to a ceasefire and agreed to engage in a United Nations-led peace process to end the war, according to the UN envoy for Yemen.

Zubaidi said foreign military aid should centre around intelligence sharing, capacity building, training and equipment.

"This approach enables local credible and effective forces to join up the effort with the Western targeted air strikes," Zubaidi said.

"This is a discussion we are having with the US and UK. The lack of a joined-up approach would only repeat the mistakes of past efforts," he added.

The United States and Britain have intercepted missiles and drones fired by the Huthis and targeted launch sites in rebel-held areas in response to attacks that have disrupted global maritime shipping.

Around 12 percent of global trade normally passes through the Bab al-Mandeb Strait, the Red Sea's entrance between Yemen and the Horn of Africa.

The Iran-backed Huthis say they are acting in solidarity with Gaza in the conflict between Palestinian militant group Hamas and Israel.

- 'Terrorist' designation -

The United States said Wednesday it would re-designate the Huthi rebels as a "terrorist" organisation due to their repeated attacks on Red Sea shipping.

The US military also launched a new strike on Huthi targets, hitting 14 missiles that were ready to launch from rebel-controlled areas.

The Huthis struck a US-owned bulk cargo carrier following the designation announcement and vowed to continue their attacks.

Zubaidi said the designation was "natural" given the Huthi attacks on ships.

"They are a terrorist organisation that carried out actions outside of UN and international norms," he said.