ADEN, Yemen, March 17 (Xinhua) -- Yemen's government force on Friday engaged in intense clashes with fighters of the Houthi militia in the country's northeastern oil-rich province of Marib, a military official told Xinhua.

"The Houthis carried out attacks on government-controlled sites in Harib district of Marib, sparking hours of intense clashes in the area," the local military official said on condition of anonymity.

The clashes resulted in the killing of four soldiers and injury of six others, he said, adding that the Houthi group also suffered casualties but didn't provide details.

The eruption of armed confrontations in Marib comes two days after the United Nations envoy to Yemen Hans Grundberg urged the warring parties to exercise maximum restraint, expressing his concern about the escalation of fighting in several areas of the country.

On Wednesday, Grundberg called for efforts toward a nationwide cease-fire and a sustainable political settlement of the years-long military conflict in Yemen.

The overall military situation in Yemen continues to be relatively stable in the past months. Since a truce came into effect on April 2, 2022, Yemenis have experienced almost a year of lower levels of violence, but "this is fragile," said Grundberg.

Yemen has been mired in a civil war since late 2014 when the Iran-backed Houthi militia stormed several northern cities and forced the Saudi-backed Yemeni government out of the capital Sanaa. A Saudi-led military coalition intervened in the Yemeni conflict in 2015 to support the Yemeni government.