GENEVA-- Aid agencies have issued an urgent call for a ceasefire in Yemen to allow vital cholera vaccinations to take place, days after Houthi rebels said air attacks by a Saudi and UAE-led coalition killed dozens of people in the port city of Hodeidah.

About 3,000 health workers need three days of "tranquility" in order to deliver more than half a million vaccines to the north of the war-torn country, according to Peter Salama, a senior official at the World Health Organization (WHO).

"We've had two major waves of cholera epidemics in recent years and unfortunately we may be on the cusp of the third," Salama said.

Last year, more than one million Yemenis were infected with cholera, a highly contagious bacterial infection spread through contaminated food or water. It can be fatal within hours if left untreated.

Almost 3,000 suspected cholera cases were reported in the first week of July across the country, the highest number since the start of 2018, according to UK-based charity Save the Children.

Without vaccinations, the conditions throughout the hot summer months could lead to the disease spreading like "wildfire" and "overwhelming an already-crippled health system", Save the Children CEO Helle Thorning-Schmidt said.

More than 22 million people in Yemen are in need of humanitarian aid, making it the world's worst ongoing humanitarian crisis.

The WHO's warning came after the United Nations' special envoy for Yemen said he plans to invite the country's warring factions to hold talks in the Swiss city of Geneva in September.

Martin Griffiths said he hoped the meeting would allow the government and Houthi rebels to discuss "the framework for negotiations, to agree on relevant confidence-building measures and specific plans for moving the process forward".

On Saturday, a representative for the Houthi rebels said the group would be willing to attend UN-brokered talks, adding, however, that they did not expect a breakthrough.