At least 3,825 families have been displaced over the past two weeks by the ongoing fighting between Yemen's government troops and Houthi rebels in the country's northern provinces.

The displaced families are mostly in Sanaa, Marib and al-Jawf, the UN Office for the Coordination of Humanitarian Affairs said in a statement on Tuesday.

Fighting broke out in mid-January in Sanaa's Nehm district, Marib's Sirwah and al-Jawf's al-Maton following a missile attack on a government military training camp in Marib that killed more than 100 soldiers.

UN envoy to Yemen Martin Griffiths called on all Yemeni parties "to cease all military activities," warning that such escalation could fail the already-fragile peace process.

Yemen has been mired in a civil war since late 2014, when the Iran-backed Houthi rebels seized control of much of the country's north and forced the Saudi-backed government of President Abd-Rabbu Mansour Hadi out of Sanaa.