US Defence Secretary Jim Mattis said Wednesday he expects the warring parties in Yemen to hold peace talks in Sweden early next month, and UN special envoy to Yemen Martin Griffiths, who arrived in Sana'a Wednesday, will participate.

Representatives of the Houthi rebel side and the government of Yemen under the leadership of President Abdrabbuh Mansur Hadi also will be present, Mattis told reporters at the Pentagon.

Mattis credited Saudi Arabia and the United Arab Emirates for being "fully onboard" with this effort.

He also said progress is being made to end the fighting, which in recent days has considerably decreased.

Griffiths travelled to Sana'a for talks with Houthi officials as part of the push for the new round of talks and after the Yemeni government announced it would participate in the peace talks in Sweden.

He was to meet rebel leader Abdel Malek al-Houthi and other figures from the group, a rebel official said.

In September, UN-sponsored talks in Geneva collapsed when the Houthi rebels failed to show up.

According to a UN source, Griffiths is expected to travel on Thursday to the Red Sea port city of Hodeida in western Yemen. Fighting there has resumed a week after both sides stopped launching attacks, although there was no ceasefire agreement.

Fierce battles took place on Wednesday in the eastern part of the city amid strikes by the coalition targeting Houthi positions, residents told dpa.

Battles involving light and medium weapons erupted on Tuesday as well as artillery shelling by both pro-government and Houthi militias against each other.

Yemen's coalition-backed government forces began their operation in June to seize the rebel-held city and its vital port, which is the entry point for some 80 per cent of Yemen's imports and aid.

Yemen, one of the Arab world's poorest countries, has been embroiled in a disastrous power struggle between the government forces and the Houthis since late 2014 when the rebels seized the capital Sana'a and Hodeida.

A coalition, led by Saudi Arabia and the United Arab Emirates, was formed months later when the rebels began to advance towards the city of Aden, the temporary seat of the government.

On Tuesday, the Britain-based humanitarian aid agency, Save the Children, said that an estimated 85,000 children in Yemen under the age of five may have died from extreme hunger or disease between April 2015 and October 2018.

The organization said it was "horrified" by the estimate, adding that for "every child killed by bombs and bullets, dozens are starving to death and it’s entirely preventable,” said Tamer Kirolos, Save the Children’s Country Director in Yemen.

"In the past few weeks there have been hundreds of airstrikes in and around Hodeida, endangering the lives of an estimated 150,000 children still trapped in the city," Kirolos added.

An estimated 400,000 children are expected to suffer from severe acute malnutrition during 2018, according to the UN, which considers Yemen the world's worst humanitarian crisis and has repeatedly warned of a looming famine.

There have been outbreaks of cholera and diphtheria in different parts of Yemen since the conflict intensified in 2015, which has also caused displacement and food insecurity due to the collapse of basic health and education services in the country.