Renewed fighting between Yemen's government forces and the Houthi fighters struck residential neighborhoods in Yemen's Red Sea port city of Hodeidah on Sunday, leaving two civilians killed, a military official told Xinhua.

"A number of residential neighborhoods and houses in Hodeidah's district of Durayhmi were struck by random shelling amid the ongoing fighting there," the local military source said on condition of anonymity.

He said that "mortar shells randomly landed on some residential houses and partially damaged a medical center in the area ... two civilians were killed and several others injured as a result of the random shelling attacks."

The Yemeni source blamed the Iran-backed Houthi rebels of firing mortar shells indiscriminately against the residential areas controlled by the government in Hodeidah.

Fighting recently escalated between the two warring rivals over the control of key areas in the strategic port city following months of de-escalation.

Last week, UN Special Envoy for Yemen Martin Griffiths called on Yemeni parties to stop fighting in the port city of Hodeidah and respect a cease-fire agreement.

"This military escalation not only constitutes a violation of the Hodeidah cease-fire agreement but runs against the spirit of the ongoing UN-facilitated negotiations that aim to achieve a nationwide cease-fire, humanitarian and economic measures and the resumption of the political process," Griffiths said in a statement.

The port city of Hodeidah, a vital lifeline for millions facing starvation, has seen a shaky cease-fire between the government and the Houthi rebels since they reached a UN-sponsored truce in Stockholm in December 2018.

The truce was seen as the first phase toward a nationwide cease-fire to end Yemen's more than five years of civil war.

Hodeidah is under the control of the Houthis, while the government forces have advanced to the southern and eastern districts.

Both sides have been blaming each other for truce breaches and recent military escalation.

Yemen has been mired in civil war since late 2014, when the Houthi militia seized control of several northern provinces and forced the internationally-recognized government of President Abd-Rabbu Mansour Hadi out of the capital Sanaa.