The United Nations Security Council on Tuesday blacklisted the son of Yemen's former president and a Houthi leader, and effectively imposed an arms embargo on the Iran-allied Houthi rebels who rule most of the country.

The council voted 14 in favour, while Russia abstained, citing the fact that some of its proposals for the resolution drafted by council member Jordan and Gulf Arab states were not included.

Meanwhile, Iran will submit a four-point peace plan for resolving the crisis in Yemen to the United Nations on Wednesday, Iran's English-language television channel Press TV reported on Tuesday.

The channel gave no further details. Iranian Foreign Minister Mohammad Javad Zarif, speaking in Madrid on Tuesday, put forward a peace proposal involving a ceasefire, humanitarian assistance, a dialogue between Yemeni factions and a broad-based government.

Zarif also called for Saudi air strikes on Yemen to end. The Iranian move was likely to draw a cool response from Riyadh.

On the battlefront, militiamen loyal to deposed President President Abd-Rabbu Mansour Hadi said they had pushed back Houthi fighters at several points in southern Yemen, including districts of the port city of Aden, the focal point of a conflict that entered its most dangerous phase three weeks ago.

After prolonged street fighting, Houthi fighters withdrew from Aden's Khor Maksar district, where the international airport and foreign missions are located.

The pull-out deprives the Houthis of a bridge to downtown areas where they face heavy resistance from local fighters.

Saudi Arabia and its Arab allies have been bombing the Houthis since March 25 to drive them from Aden, the most important city still loyal to Hadi.

The Houthis, northern-based Shi'ite Moslems, seized control of Yemen's capital Sanaa in September, confining Hadi to the presidential residence. He fled to Aden in February then escaped to Riyadh last month as Houthi forces closed in on the city.

Saudi Arabia and other powers accuse Iran of arming the Houthis and interfering in Yemeni affairs. Tehran denies giving military support to the Houthis.

"This issue should be resolved by the Yemenis. Iran and Saudi Arabia need to talk but we cannot talk to determine the future of Yemen," Zarif told a news conference in Madrid.

Zarif also said the air strikes "are simply not the answer. All operations should end on land and from the air".

On Monday, Zarif had called for a new government in Yemen and offered to assist in a political transition.

The offer was unlikely to please Riyadh, which says it is protecting Hadi and his government-in-exile from the Houthis.

Southern militia sources said they wrested control of an army base loyal to the Houthis after heavy fighting on Monday night near the Balhaf liquefied natural gas (LNG) plant, in southern Shabwa province on the Arabian Sea.

Yemen LNG, the company managing the facility, said it had halted production due to insecurity and was evacuating staff. Militia sources said they had moved into the port to secure it from looting.

Militiamen said their fighters had killed around 40 Houthis and allied soldiers in the southern province of Dhalea over the past day, although this could not be independently confirmed.

A cargo plane chartered by Medecins Sans Frontieres (Doctors Without Borders) landed in Sanaa on Monday with 15 tons of medical supplies.

The MSF head of mission in Aden, Marie-Elisabeth Ingres, said the supplies should allow the organisation to help out other parts of the country but supply routes needed to be kept open and fighting was hampering its work.

It is trying to establish a supply route by sea from Djibouti directly to Aden, she said in a statement. - Reuters