"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," Martin Griffiths told reporters in the capital Sanaa.

Griffiths on Tuesday wrapped up a three-day visit aimed at brokering negotiations between Saudi-backed loyalist forces and Huthi rebels.

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

"We are working very hard, focusing every day on moving forward in the political process," he said.

"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."

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

Multiple rounds of UN-brokered talks between Yemen's Iran-backed Huthi rebels and the country's government, allied with Saudi Arabia, have failed.

The Huthis seized control of the capital in 2014, driving the government south and sparking an intervention the next year by a military alliance led by Saudi Arabia.

More than 22 million people are now in serious need of aid, with 8.4 million on the brink of starvation, according to the United Nations.

The world body considers the situation in Yemen the world's worst humanitarian crisis.

The conflict has left nearly 10,000 people dead in what was already the Arab world's poorest country.