The UN envoy for Yemen said Tuesday he was "very concerned" over fighting for the rebel-held port of Hodeida, as government forces close in on the main gateway for aid into the war-torn country.

Martin Griffiths was speaking as he wrapped up a three-day visit aimed at reviving talks between Saudi-backed loyalist forces and Huthi rebels.

"Apart from the avoidable humanitarian consequences of such a battle, I am also very concerned about the impact (on) chances of a political settlement of this conflict," he told reporters in the capital Sanaa.

The envoy, appointed to the post in February, told reporters at Sanaa airport that his talks had been "positive" but warned of the impact of the Hodeida fight on civilians.

"My aim is to restart negotiations which have not taken place for a very long time -- for too long -- and I want that to restart in the very near future," he said.

Multiple rounds of United Nations-brokered talks between Yemen's Iran-backed Huthi rebels and the country's government, allied with Saudi Arabia, have failed to find a solution to the Yemen war.

Three years of fighting have claimed 10,000 lives and pushed the country to the brink of famine.

The battle for Hodeida port, controlled by the Huthis, has killed more than 100 soldiers and insurgents in less than a week, medics and military sources close the government say.

The rebels, who have so far refused to withdraw from the port, claim 418 loyalist fighters have been killed.

'Finger on trigger'

Griffiths is due to report to the Security Council on June 18 on his peace efforts.

The UN recognises the cabinet of President Abedrabbo Mansour Hadi as the legitimate government of Yemen.

The Iran-backed Huthis have regularly accused the international body of bias.

In Yemen, Griffiths met with Mahdi al-Mashat, head of the Huthis' political council, and representatives of the General People's Congress -- a party founded by former president Ali Abdullah Saleh, killed in December.

From 2014, Saleh was allied with the Huthis in the fight against the government, but he shifted allegiances last year and was killed by the rebels.

Mashat was quoted by rebel news agency Saba as saying that "just as our finger is always on the trigger to defend the sovereignty, security and unity of our homeland, our other hand is always extended to peace if all parties are committed to it."

Conditions for withdrawal

Yemeni political sources say the Huthis have put in place a list of conditions in return for their full withdrawal from the Hodeida port.

These include paying military and civilian employees in areas controlled by the Huthis, reopening the international airport in Sanaa and allowing commercial traffic to flow through Yemen's many ports.

"The Huthis have taken a tough stance and have set conditions that would prevent any political solution," a senior Yemeni government official told AFP.

The UN has warned that any operation aimed at seizing Hodeida itself would disrupt the entry of aid shipments to Yemen, 70 percent of which flow through the rebel-held port.

The port has been a point of contention in Yemen's war since Saudi Arabia and its allies intervened on behalf of the government in 2015 after the rebels seized Sanaa.

Hodeida is crucial for aid deliveries as Yemen teeters on the brink of famine.

Saudi Arabia says it is an entry point for weapons to the rebels, which it accuses regional rival Tehran of supplying.

The Hodeida offensive is spearheaded by Saudi Arabia and the United Arab Emirates.

A spokesperson for the Saudi-led alliance on Tuesday said government forces were only nine kilometres (six miles) from Hodeida.